The criteria that people set for being "well known" and "respected" however, according to what people have said is.....1) Having a high post count and 2) Being "active" on the board, which translates once again, to number of posts.
Anyone can get a high post count by freeposting, in my opinion, reference should be had to quality not quantity of posts, therefore making the post count obsolete when choosing mods. And as for being active, like Rukas said, being active on the board is guaged best by reading it, something which may not be visible to others.
As for fear of "power tripping" and the closing of threads - mods are accountable to members as well as admin when they make such moves, therefore, should any injustices occur, they will be dealt with - if and when they occur at all.
For the record, I would never deem to "control" my forums. Members do. They are the ones that create the topics and generate the discussion, they create the content - MEMBERS control the forum. All I do is close threads that break guidelines.... in short, moderate it.