[Big_Jim]

I prefer leading with bottom or middle pair to leading with TPNK.

That way, your outs are more likely to be clean, and you can give up more easily when called.

Also, your implied odds are a bit better, since they won't expect you to be leading with middle or bottom pair.

Whether or not I'll do it has to do mostly with board texture, number of players, and of course, reads.