I've noticed the same thing, of course. I tend to notice similarities to myself and weigh in on those threads, while ignoring the ones that don't resonate with me. So there's an additional bias, although it may not actually cause incorrect typing.
Typing actors is very difficult (let alone their characters). Even the public side of an actor that they let you see is not necessarily going to reflect their "real" type that maybe their families and close friends see.