I think that probably actually applies with friends as well, but at least with friends you can take it gradually. Learn one thing, then another, then another, to slot it all into a new conception of personality over a long period of time. When you're learning about an actor it's usually by reading an article or interview or something which has new fact after new fact after new fact.
For instance, I recently discovered a lot more about Paul Gross.
So the first thing was; he is really a lot older than I'd ever given him credit for being (easy mistake to make).
Second thing; he is a complete and utter goofball. Geeky geeky geeky adorkable goof.
Third thing; as well as being a goofball he's a serious playwright who has had critical acclaim and ya ya. After seeing them, I knew he'd written episodes of dS, but I never really connected that with having actual tangible success (and failure).
So here he is; he's an actor, a singer, a writer, a geek - he's so much better and more complex than I ever could have imagined, and I love him for it. Oh and, it's not like I ever thought he wouldn't swear, it's just that hearing him say "fuck" is wrong on so many levels. I mean, intellectually you know he's not Fraser, but there's a part of you which believes he is anyway.
It really goes to prove that those stereotypes of extremely good-looking people being bubbleheads is just wrong. And also, that it's so easy to fall into the trap of thinking within stereotypes even if it essentially goes against everything you believe in.
And, and! Knowing that PG was acquainted with the dS slash community now makes me realise why this show was my slashy muse. He's such a wonderfully bad man. No, seriously, what a great sense of humour. He totally played up to that when writing CoTW. That rocks so much. He rocks so much.