Hmm, I think you'd have to watch it and see what you think--I'm not really attuned to the nuances of the RPF issue. (I don't read it but have no moral issue with it.) Some of the fan characters know that Sam and Dean are real and others don't, but the show mostly plays it on a meta level as an interaction with their own fandom, so it's more dealing with the relation of fans to fantasy characters. (Although, of course, Sam and Dean themselves are aware of what's going on, and Dean in particular is bothered by people using their "real" suffering for entertainment, though he seems to adjust his perspective a bit once he sees that fandom is an inspiration to fans, something that makes their lives better.)