That's more an accusation than a question, but it's one of the common ones I encounter.
The whole nature of evaluating the goodness or badness of something arises from how that thing relates to some purpose or goal. Is a rain storm good or bad? Well, that depends on whether you are a farmer hoping for a drought to break or a backpacker hoping to keep his sleeping bag dry. The goodness or badness isn't an intrinsic property of the thing itself (as if there's drop of goodness or evil somewhere inside the thing), but rather how the properties of the thing relate to some contextual goal against which it is being judged. It is important to note that this is not in any way the same thing as a relativist view of the good. The fact that something impedes or promotes a goal is a matter of objective fact which can be studied and evaluated and there are right and wrong answers to the question. It's not just a matter of subjective or relativist opinion, it's a matter of objective fact.
When it comes to man-made objects there are some special considerations that become relevant which make no sense when it comes to natural phenomena. You can't ask a question about the qualities of a natural object with regard to their purpose or "goal orientation". A stone is hard not because it seeks to serve some purpose but because that's just how stones are. The moon is grey because of the nature of the materials that make it up, not in order to achieve some goal. By contrast, you can ask such questions about man-made objects and situations. The head of a hammer is hard because it increases the impact of the head when it hits something. A wheel is round so that it will roll smoothly. Most manmade things are created as they are in order to achieve some goal, and to evaluate such things the proper way to do it is by measuring it against that goal. To use Aristotle's example, the reason we have knives is for cutting things. To that end we say that knives are good knives if they facilitate cutting better than others. A strong and sharp blade, a comfortable handle, and so on are key features of a good knife. In some cases a knife might have a special purpose such as cutting fruit, meat, metal, or in fighting with people, and in those cases additional properties might be good criteria for judging the goodness of a knife such as its size (not too big or small for the thing that is intended to be cut), creating a jagged cut or a smooth one (jagged perhaps being better for fighting since it would be more painful but worse for fruit). The point here is that depending on the purpose one intends for some man-made object, different properties might be good or bad even though you can still make generalizations about that class of objects.
Now let's consider how this applies to art. In general the purpose of art is to express ideas, and in particular it is the expression of ideas by the means of selective recreation of aspects of reality (as opposed to other means of expression of ideas like journalism, exposition, lecturing, screaming, etc.). Given that general goal, there are some general things you can say about any of the arts with regard to what makes for good art.
One is a set of issues related to the circumstances of its creation. For example, if the artist has excellent control over his medium (you could call it "craftsmanship") his ideas are more effectively transferred to the medium. Weak craftsmanship means that the effectiveness of the expression will be undermined.
Another is cultural context, which is how the work relates to the cultural context of the audience. What I mean by this is that a poem written in Chinese is going to be meaningless to most Americans so if you hope to express something to them it would be best to write your poem in English. The same goes for traditional matters of the medium. We should not pretend that the audience has never seen a painting, sculpture, novel, or string quartet before. We should make accurate assumptions about audience understanding and experience in making art for them if our art is to be of maximum efficacy.
Another is sensory accessibility, which has to do with the ability of the audience of the work to apprehend it effectively. A painting too large or too small to see, a symphony too quiet to hear, or a sculpture in a room too dark to see or feel would be ineffective in expressing their artistic ideas.
Another is comprehensibility, which is the property of the work that allows the audience to comprehend the intended expression. A work of art whose comprehension depends on esoteric knowledge (like what the artist had for breakfast for example) can't very effectively express anything to anyone but him. There's nothing inherently wrong with this as long as the artist and his promoters remember who the art is for. A work intended for the comprehension of a single person doesn't belong in a museum. A work exclusively intended for the comprehension of Masai warriors belongs where those people can see it, not in some American museum. It isn't accomplishing its artistic goal anywhere else.
Another general category has to do with pure sensory factors regarding the pleasure or discomfort of experiencing the work. Pleasant colors, somber hues, harmonious sounds, discordant notes, murky or confusing patterns, beautiful sculptural materials, and so on can on a very general level imply something about the work that may or may not be compatible with the meaning that is being expressed.
There's also another general issue of "design unity" which allows a work to hang together with a coherent meaning rather than having divergent styles, distractions, and inconsistent meanings. I am sure that you can think of more principles of this general kind, but I wanted to just point out a few examples to give you an idea of what these kinds of principles are and how they can relate in a general way to the quality of an artwork and how they can be objectively evaluated.
As we consider specific arts by themselves such as painting, there are several general kinds of issues which lend power to the expression or detract from it. For example, the effective use of composition to highlight important aspects of the work and minimize unimportant ones (and influence the order in which the work is experienced) is a key tool of the artist. Another is the choice of subject as appropriate to the idea being expressed. Another is the effectiveness of the use of color in setting moods, bringing attention to aspects of the painting, and diminishing attention on unimportant parts. Another is the use of illusion to create a sense of reality or unreality of a scene, there are a lot of ways of doing this. There are others specific to painting, but I think you get the idea, and I'm sure you can come up with more yourself for the other arts.
Lastly, we can consider the effectiveness of various properties of a painting with a specific subject in mind and ask whether in a particular case the design, composition, color, brushwork, craftsmanship, selection of subject, etc. effectively accomplish the expressive goal of the work or not. It is hard to make firm generalizations about this because there are so many options to pick from, but on its own terms you can judge how effectively a work pursues its own particular expressive goals using its own particular combination of artistic tools.
This is not just a matter of how you feel about the work or whether you like it (though such emotional reactions are an important indication of if and how an artist is using his medium to express things to you). To evaluate the objective quality of a work of art one needs to determine what the expressive goal is (which ideally should be easily determinable by looking at it rather than having to reading a biography of the artist or even the little plaque next to the painting) and then judge how the tools of the medium are used to pursue that goal. Again, this is not a matter of emotional preference, nor arbitrary preference, nor conformance to some kind of formal set of rules, it is a matter of judging the effectiveness of the work through an analysis of how the artistic tools are used. The tools themselves have properties, and therefore there are right and wrong ways to use them and formal methods much of the time provide useful formulas for using them with maximal effectiveness, but that's not anything like claiming that there's some kind of static formula by which an artist can use a cookie cutter to pound out works by just applying a recipe without thinking and judging the consequences. It is also different from the idea that creativity is a matter of ignoring and eliminating considerations regarding the properties of the conceptual and physical tools that create art, the nature of art, the medium in which the art is expressed, and the audience's needs and abilities. Real creativity consists of discovering effective ways of using these tools in order to achieve the most effective kind of expression.
There's one more kind of criteria on which art ought to be judged and that is the nature of the message itself. Some works of art express ideas which are true and others are false. Some promote views which are good and others which are evil. Some tend to enlighten the viewer and others tend to degrade his character. This evaluation is different from the issue of pure artistic quality, but it is not an irrelevant question, and it is one that generally gets too little attention these days as nihilists seek to eliminate all such evaluations from life. For example, there's something wrong with an otherwise excellent painting that promotes the idea that ignorance is bliss that isn't wrong with an equally excellent painting that promotes the idea that ignorance is a cage.
Alas, the 20th century art world was ruled by people teaching that there are no right and wrong ways to create art, that no art is better or worse than any other, that creativity means ignoring the properties of the medium and the audience, pretending that they either don't exist or can be anything, and that novelty is itself the goal of art, not the actual artistic expression of ideas. This whole line of thinking is nonsense, and fortunately, the world seems to be slowly turning away from that view. When it comes to "arrogance", which is more arrogant, to observe the facts and draw rational conclusions from them or to insist that understanding is impossible and that anyone who claims to know anything is wrong (and a terrible person!) merely because of the claim to know anything at all? That's arrogance of the kind that condemned Galileo, and it's alive today in our artistic institutions, and it needs to be exposed for what it is... arrogant, strutting, self-righteous ignorance and error.
