Personally, I hate a lot of modern and post modern art. Some of it, like the silent composition, or a completely blank canvas, intended to make a statement, are purely stupid to me. Picassos guernica to me, is nothing special, it looks like a childs attempt. The concept I get, but II feel I only enjoy art I can appreciate on a technical and aesthetic level. Yet there are technically brilliant pieces of art that I don't even get a reaction to, I find them boring. Your own personal life experience will shape what you consider to be "good art". Which sounds like I'm arguing in favor of subjectivity, yet you can still make bad art, in my opinion. It's just not binary, things can have redeeming features, ita a rare piece of art that doesn't even have one.