If you're with the fast guys, then they'll probably be cool and humble and happy to see another cyclist out on the roads. This good attitude comes from having been stomped on by lots of faster guys in lots of races for lots of years. They'll also drop you immediately.

If you're with the "B" guys, then it's crap shoot. A lot of these freds take themselves way too seriously, and some of them think they're actually 'fast guys'. These are the ones who are actually responsible for a lot of the 'road nazi' stuff you hear about.

The "C" group will probably be a mixed bag of folks, some of which will be dressed just like you so you'll fit in fine.