Actually, I find confident people much easier to evaluate - over time it's pretty easy to tell a bullshitter from someone who knows their stuff. When talking to people who hedge their bets too much (or worse still, don't speak up at all unless I have the time to prompt an answer out of them), I'm left with an unclear idea of their original position, so it's much harder to decide whether to trust them.

My favourite people are still those who state their conclusion, but will happily rattle off the list of assumptions they used to get there as well as how confident they are in that conclusion. But those people are pretty rare.