I've seen a couple coat colors that don't seem right. There was one where the cat was dark blue with a very light blue around the muzzle extending up to a strip between the eyes. It was basically your normal white spotting, but it's not genetically possible to have pigmentation in that pattern (barring chimerism, of course).

There were also a couple questionable ones where they had very studdy cheeks, but were tricolor (calico, tortishell, patched tabby). They distinctly looked like intact males, but you need two x chromosomes to have a tricolor cat. Or chimerism, of course, which I've learned over the years makes it impossible to ever say a specific pattern isn't possible.

It did get me wondering though, with the fact that most apparently male cats with tricolor markings genetically have an extra X chromosome, whether they would still get the big stud cheeks. I'd imagine they would, since they've got a Y chromosome and then I assume the X chromosomes turn on and off randomly the same way they do in females.

In less nerdy news, if you go through about a dozen pictures, you'll find that some of them are out of proportion or have their mouths open, but have the coat color in the mouth.