I remeber a PUG for SSC once in TBC, it was fun. Kara/Grull were constant. And pugs were constant in Wotlk.
Ever since LFR nobody pugs in chat anymore because its easier to click a button. And I don't know about other servers, but on my server raiding guild are dying out. We used to have a very good raiding guild I think they were like top500 world, or even better. But they quit at the end of Cata. Right now #1 guild on my server is a guild who used to be #40 during TBC. The majority of guilds quit.