OK, finally remembered to check with my friend Joseph about this. Here is his reply:

Ah, there is a problem with compliments and mitzvot.
The Chofetz Chayim said in his laws concerning loshen hora (evil
talk), that even complimentary phrases can have an unfortunate effect
of producing either jealousy or resentment, so that one should
restrict oneself to polite language only, never complimenting,
insulting or talking about another fellow human being. Then again,
the Chofetz Chayim was also incredibly humourless ....