If you are putting your work up here on a very public forum, you should be adult enough to take the heat. Art is in the eye of the beholder, and everyone sees things differently. This is a WORLDWIDE community, not just your personal 'buddies' site. If there is a piece that you find offensive, yes, by all means, let the artist know, but be knowledgeable about it. Just saying, "Hey, dude, your stuff sucks" is just about as worthless as what you think you're commenting on.

Do I think it's art? What I think almost doesn't matter. I will quote The Joker from the original Batman (Douglas/Nicholson), "I may not know art, but I know what I like."

Since pre-recorded history, people have been making art. Heck, it is art that denotes recorded history from pre-recorded history. Art is part of our higher brain functions. Therefore, I think, therefore I can appreciate art. Thank you for thinking. That's what makes it art.