What? Full of Fraser Valley rednecks and Stanley Cup rioters?
In a word, yes. Cultus Lake is the "party" campground. Lots of trouble with drunken louts. Noisy, busy.
Another option is Porteau Cove PP which just a little north of Horseshoe Bay. It does straddle the shore and the BC Rail tracks so don't stay there if you can't sleep through a rumbling train.
Porteau Cove is very nice. The trains are infrequent, and there's quite a bit of forest between the campsites and the railroad tracks.