I just don't add people that quickly. Everyone, and I mean everyone in my list are people whom I've known/talked to for a long time while skilling or from clan chat. I've had one too many encounters with people who just want to use/befriend me because I'm a mod or I possess a certain item they want to borrow.

 

Pssh I only talk to you for your items. Can I borrow anything today? Just for a little while?

 

 

 

But back on topic, the best way for me is to add them, say a few things, then say I'm turning chat off and remove them.

I have a lot of friends I never talk to. I don't really know what's holding me back from deleting them, probably laziness, since my list is almost full. But yeah, mostly, my private chat tab is a lot of "... logged in" and "... logged out" with an occassional question or comment or whatever.