I like to do that every now and then to make it look customized. Though putting a picture of a Kioka over a natural Gondra to try and scam someone wouldn't be right, lol. O.O; For example- I'd take an image of an Amber Otachie, edit the image to make it looks like it has fire coming out of the paws, and then put it over the image of my Amber Otachie whose overall character revolves around mastering the magic of fire.
8D