Here is example... Lets say you finished a 3d character. By "finished" I mean you're done with modeling/sculpting,texturing,rendering. And you see there are some problems in anatomy for example or maybe in texturing, and you overpaint those parts in Ps. Thats kinda "faking". But yea, it's all about context and what is the…
Well I guess it depends on what you want to promote with your 3D stills, if it's for example meant to showcase your realtime 3d skills for employers it might not be a good idea to do a paintover on top of that and call it realtime.