In any form, if the art was not made by you and you are claiming you made it. stop. how would you like it if someone took something you made and said "Hey you spent all your time making this, but guess what. its mine now because i said so." then posts it and starts CHARGING MONEY for YOUR work.
Guys i have to point out a user whom i had problems with almost two years ago commenting "good but not as good as my art" in deviations all over the place. Not just that they Steal art from people and then try to sell it like it is their own. I will be linking them below. Maybe you all can help me get them off of Deviantart and make them think twice a