So I had a couple of stuck pedals on my rummage sale mountain bike (I wasn't the one that put them on--I know to grease them beforehand). After trying WD-40, PB Blaster (letting it soak in over 24 hrs), beeswax, and pouring boiling water over the crank arms, nothing worked. They were stuck. Yes, I was turning them in the right direction, BTW.
I finally broke down and got a propane torch from Autozone, heated up the crank arms near the pedals, and they came off in no time flat.
I'm also able to use the propane torch for soldering copper pipes and toasting marshmallows. So I think I definitely got my money's worth.