Originally posted by robgski When it looks over processed, back up a step, that's enough.
Best, most succint answer, and it has the virtue of being true.
If it's something people would comment on, even in a complimentary way, it's too much. Just enough is the point at which you've made the picture look as good as you can without making it noticeable. I've used the analogies in the past to womens' make-up and theatrical stage lighting - it gets past making improvement and starts being a detraction the more anyone can tell it's there. If someone sits through a play and says something about how wonderful the lighting was, then the lighting designer failed, because his job is to make the play plausible to the audience, not to show off his own talents.