[peterbessman]

Why not? It's perfectly reasonable to judge the quality of a work by the degree to which it succeeds with its desired audience. To quote Paul Graham:

"Art has a purpose, which is to interest its audience. Good art (like good anything) is art that achieves its purpose particularly well. The meaning of 'interest' can vary."

http://www.paulgraham.com/goodart.html

As to restroom graffiti in a dive bar... what's the problem? If it was in the vatican lavatories, sure, you'd have a case. Where I'm from? Not so much. A lot of joints herebouts have sharpies in the head, should the muse visit you whilst micturating. I guess we're sufficiently horrible. Or awesome.