Yeah, Proper does give several new social interactions. But other Sims didn't seem to like it when my Proper Werewolf tried to discuss matters of etiquette with them. It's supposed to be a friendly interaction, so I don't know why the ones she tried it on always reacted negatively. Maybe it had something to do with their traits, or maybe it was just that they'd seen how werewolves eat and figured anyone with table manners like that is in no position to lecture others on etiquette! 
I've had no problems discussing matters of etiquette with sims friends or above and all problems doing it with acquaintances, no matter the traits. It makes sense. I'd be ok with a friend talking about how it's important to chew with your mouth closed, but would understand something like "watching you eat is like watching a farmer feeding his pigs" if I'd hear it from someone I've just met.
