In the worst cases, you get clipping and/or muddy bass. (Probably that muddy bass *is* clipping, but maybe clipping in that sound region sounds muddy.) Clipped treble or upper midrange is particularly offensive, at least to me.
Other times you'll just get reduced dynamics or dynamic range, and there are probably other symptoms of which I'm not aware.
Other times you'll just get reduced dynamics or dynamic range, and there are probably other symptoms of which I'm not aware.