Assmongerer.
Well, man, you're certainly able to draw perfect asses. I mean, the ass of this drawing is perfectly ass-tacular, what with the ass and the skirt and the ass. Did I mention how great that ass is?
However there are a great many things wrong with this picture. Not that ass. Damn, I'd hit that. No. Great many wrong things with this picture. The hair is completely bland, sporting a wholesome three sparse layers of shading that are completely at odds with the rest of the picture - even if the hair was "directing" the flow of shading for the picture, the body (ass included) and clothes don't show it, sporting lighting from another two sources as well as completely ignoring the presence of the hair. My advice would be to choose one direction for the lighting, stick with that, and try and put more detail into it, while shaping the light flow around that spank-magnet.
Next issues would be the skirt. It's length is at odds with itself, longer at the sides while shorter over the big booty itself. Now, while I definitely appreciate what you're trying to do, there is no real existing fashion that employs those tactics and any attempt at foreshortening doesn't really cover how much shorter the ass-flap is. I'm not telling you to lengthen that one part of the skirt to make it fit in with the others, no. I'm telling you to shorten the rest of it, just to show off more of those gracious hips, hey?
Now, i really should move onto the way-too big forehead and unrealistic tiara and boring gradient-based background and poorly proportioned breasts, but all I really want to concentrate on is the ass so let's head back to that, shall we? The hips are out of proportion to the torso and shoulders - while the characters (whose name and face and whatever else beside the ass is not important) is turned, it's obvious that the shoulders and torso are too small for those hips, try lengthening them out a tad, or just shading them more accurately to make them seem lengthened out more.
So, overall, nice ass, ass and ass. Can't say much for the rest of the picture. Should really rate this lower but you get an 8 for perfect ass-drawing.
Sexually depraved? What are you talking about?