One thing that really bothers me is stealing artwork and calling it your own. This happens to a lot of artists, especially those who paint, draw and sell prints. I'm not saying ideas are completely untouchable, especially the vague or popular ones. You can glean inspiration off another artists. What I'm talking about is downright copying or, for f*cks sake, selling the exact print as your own.
While perusing Etsy today, I stumbled across several very familiar paintings for sale by Sam315.
Pretty cool. Great concept, very unique, Heck in the Pocahontas painting, the skull she's wearing on her belt is a 3D medium sticking off the canvas. NEAT! Oh wait, what's this?
Huh, well this is a suspect situation. I'm not saying that one artist can't redo another artists idea better, but I think it's pretty obvious whose pictures came first. The bottom pictures are by an artist by the name of Jeffrey Thomas. Aside from being amazing, he has an entire collection of other Disney Princesses being creepy and scary. Granted the first paintings are very different mediums, they are copies nonetheless of someone else's art.
Art theft seems to be a problem for DeviantArt users since your art is just up there on the web. It drives me insane but I hate watermarks. If someone wants to use another's idea, at least make some attempt to alter the image. Never paint the exact same thing or copy every detail for the matter. Artistic representation is much more flattering than flat out copying. Fair use and Creative Commons were written for a reason.