I have no problem with the specific work of art "Gnaw" being considered art. It needn't be good to be considered art and it can be a complete piece of trash compared to other artists. I would say that Janine Antoni is somewhat talented as she has done sculptures from eating chocolate and lard.
http://www.pbs.org/art21/artists/antoni/art_sculpture.html#
That's a decent link to some of her work, Gnaw included. Lick and Lather is a find demonstration of what she can do with sculpting.
If someone wants to spend money on it then no big deal. They wasted their money, not mine.
As far as comparing musicians to artistic ponzi schemers is it really no different? Performance art is just that, a performance. Much of it can be compared to Britney Spears who is an entertainer with a lack of good musical talent. People still pay money to see her, though I have little idea as to why. There are those I've talked to that feel Britney Spears is a very talented artist and it is futile to argue with such idiots.
Growling again is subjective. Some will find it abhorrant and talentless and others will find a quality in there like Kaotik where they can discern the different pitches and tone. That's not to say it is good music again, as that is highly subjective.
My personal opinion of growling is really that it can make a good song. Opeth is a fine example of that where the guy knows how to growl but he can also sing his ass off. Plus the composition of their songs makes for a good time in bed.
Quick edit:
I've bought many pieces of art that are of significant value to me because they strike certain thoughts or emotions within me. Some of this art is so abstract some of my friends just don't get it and I'm fine with that. They've got works of art hanging on their walls that I personally find nothing more than pieces of trash, but they like it for whatever their reasons are so I can't knock them on it.
I'm also a big fan of traditional art, especially Dutch Renaissance. They knew what they were doing!
