Stealing artwork, especially for commercial use. Including posting artwork that's not yours and claiming it is.

Spam via Notes. "Check out these hot and horny teens: sellingtobigcompanies.blogs.co… "

Disabling comments on -all- your work. Why are you on DA? If you just want favs and no interaction, that's what Tumblr is for. (there are exceptions)

Completely negative or wholly nonconstructive critiques. (there are exceptions)

Spamming DA member pages with contests. There's a place for contests on DA and it's not my page.

Trolling. "Ever use your anus to paint? If so, do you let your sister watch?"

Being an elitist twat. Some DA members are very young, beginners, non-artists or generally inexperienced, that doesn't give more experienced members/artists the right to treat them like lessers or outcasts.

Posting other peoples artwork without permission and/or credit.

Style rips. There's a difference between influence and purely copying other artists styles. It's not flattering, it's lazy and pathetic.

Other via comment.