I have to admit the only people I ever party on my cleric are my guildies/people I know through KQs/etc. One reason is because I cbb finding a party, and another is that I don't usually talk to people I don't know (well I haven't met many that are talkative) so it's boring.
Though I have to find parties on my mage these days. Many spots where I need to complete quests in are taken by other people, so might as well party. I don't ever seem to party clerics though, partied a lot of fighters.