This exchange, from the end of Mirror, Mirror...
Kirk: Probably. However, that Jim Kirk will find a few changes, if I read my Spocks correctly.
McCoy: Jim, I think I liked him with a beard better. It gave him character. Of course, almost any change would be a distinct improvement.
Kirk: What worries me is the easy way his counterpart fitted into that other universe. I always thought Spock was a bit of a pirate at heart.
Spock: Indeed, gentlemen. May I point out that I had an opportunity to observe your counterparts here quite closely. They were brutal, savage, unprincipled, uncivilised, treacherous; in every way, splendid examples of homo sapiens, the very flower of humanity. I found them quite refreshing.
Kirk: I'm not sure, but I think we've just been insulted.
McCoy: I'm sure.