Pretty much this. I've been through some seriously nasty stuff in my life - but I don't talk about it. Like, ever, outside of private conversations with fairly good friends [and even that is rare] - but I'll say 'Oh man, I totally get how that character feels.'

However, by what you can see I'd probably seem to be a 'sheltered fan' when that really isn't the case.

Tl;DR: Anon above me is right - you really can't tell what a person has been through, or how it's effected them.