I think the big problem is the "filing the serial numbers off" part of it. I never read "Masters of the Universe", but it seems to me that it didn't actually involve all that much in the way of vampires or werewolves. Whereas if you had a fic about time traveling robots, a human resistance from the future, and UFAI, it would be really hard to get people to believe that it wasn't Terminator. Or if you had a story about a superhero who works as a reporter and his evil genius nemesis, people are going to see that it's Superman unless you file the story away so hard that you'd be better off rewriting it from scratch.

The best way to go about it seems to be to just start with a story that doesn't rely too heavily on whatever canon you're working with, so that once you have the readership, you can make the jump without having to refactor too terribly much.