Oh, I know what you mean.. I'm the art for a webcomic of my friend's, and she wants all these backgrounds but I can't draw them at all... >.< All of it is really simple - which is sad when I put so much time into the foreground.
My problem is that if I put a lot into the character and do a backgroudn I want ti to be as good as the character is and that's usually just not possable.
I know exactly what you mean! What's really frustrating is spending tons of time on a contest entry and doing most of the work on the background, all for naught. +glares at contests+