A few times I have composed a scene on ground glass and then preferred to print it flipped... probably because it fit my memory better.

I have noticed that quite a few scenes look equally good to me when printed either way, while some seem to be strongly 'polarized' - tending to look much better one way than the other.

Anyway, sure, I think it's okay to do as long as it doesn't fundamentally misrepresent something e.g architecture and such. It'd certainly not be appropriate in photojournalism.