I used to work stripping furniture. Nasty stuff, even the "friendly" products. You don't really get a feel for the power of those stripping chemicals until you've spent weeks working around them. Cast iron is porous, isn't it? I don't think I'd cook food in a pan that had been in contact with any type of the industrial chemical cleaners that have been mentioned so far!
But then, maybe that's just because I'm originally from California! :D