It's probably true, "visually" speaking (as opposed to "accurately" speaking) because of the background image grain.
I have two good ways to deal with most of the complains abiove, sadly, first one I don't like and second one is no good for suh a subject:
1) turn greyscale. tint is usually what screws up incrustation, no mmater how much time you spend on it, the global lighting tint will mess things up, because it is not, contrary to what it's called, global. It varies over the pic, and for the incrustation, it has to vary the same way. It is difficult to actually spot, but the general feeling itself will stand out and be clearly visible
2) add subtle noise. The background is grainy, the rendered incrustation is not. No need to say more I guess.
All in all, composition is a thing that needs more time than what I obviously want to spend on it, so I'll give up on that. (darn, an nobody even noticed the reflection of the mob in the water ~~ )