Almost every time - it gets me right in the zone. If I'm going to meet a plump blonde I'll watch porn with a plum blonde in it, or for a slim brunette teen, I'll watch that.
I'm not in agreement that all porn is fake; on the contrary there's a lot of excellent amatuer porn on t'internet, slutwife gangangs and DPs etc. Through the visual quality is not the best (though some is surprisingly good), it is the real thing, because it's ordinary people like us.
So much so that I'd say it was a bigger turn-on than 'professional' porn where the actresses are impossibly beautiful and actors enviably horse-cocked; some of the so-called professional porn actresses are so used to having three dicks in them that they look utterly bored, and the 'oh yeah fuck me fuck me' dialogue is so bad it's funny. GIve me the enthusiastic amatuers any time!