I think it was a graduall thing for me, getting over gore. Now I can watch any Saw-type movie without flinching.
Except in Saw III, where he has the hooks in his skin. It's not the worst trap, but for some reason when I saw that the first time I felt pretty sick, I had to get up and drink some water. I finished watching it, and the Rack trap didn't bother me at all, I don't know, it was weird.
But I remember as a kid seeing the part when my dad was watching Aliens when Bishop got impaled/ripped in half that freaked my ass out. I didn't know he was an android and seeing that guy erupt in a fountain of milk scared me to death.
But I can take about anything now, it's like building up an immunity