and don't bother explaining to the people...they just keep coming...(annoying)
At the time when you originally posted this deviation, you did not know the artist, so you obviously didn't ask them before posting this image. That's pretty simple. No one should have to come and tell you they made the art. YOU should have to find them and ask before you EVER post it. Not only that, but on many of your deviations, you don't even credit an artist at all.
I do understand that you post it as a render(not claiming you actually drew it), but you ask others to ask for permission to use it when it's not yours to do so with. This is actually pretty ironic that you think others should ask you for permission, but that you do not do so for others.
If you got in trouble for your actions, it would only be just. You are doing something very wrong. I know you aren't the only one on this site like that either, but that doesn't mean you should be doing this. Many artists would be very upset to find out you merely remove the background from their art and repost it without ever asking for permission. Can't you see it from the other side? This doesn't mean you can't keep making these, but you have to do it with consent from the original artist. If you can't find the original artist to ask, or they don't give you permission, you shouldn't be posting it. It's as simple as that.