I think that, if people want to see the type of art you accept, they should take a few seconds to look at the gallery. Sometimes, artwork is borderline, and people will submit regardless and take a gamble because they aren't sure and feel like their piece just might be good enough. However, I do disagree with your policy of having the moderators send individual messages to the people whose pieces have been rejected. You never know who you're interacting with online, and I'm sure your moderators have gotten a lot of hateful and crazy messages in response to their obligatory "I'm sorry" letters. I just don't think they should have to deal with that.