There's been a bit of backstory on how various Trek
species view other species. The existence of a Klingon restaurant on DS9's promenade shows that there's a market for Klingon cuisine, despite its apparent grossness (their music, not so much.) It's been implied that Vulcans often appear in 24th C pornography.
Humans appear to be regarded as useful cannon-fodder given their predominance in Starfleet.