[quote=@Penny]
<Snipped quote by Starboard Watch>

I find the opposite is true because I just dont have the mastery over many fandoms to be able to be faithful to them. In an original world nothing that I come up with is going to be wrong. 
[/quote]

I think it depends upon one's mastery of the fandom they're working within. I could easily create a convincing RP set within the Star Trek universe, on-par with my ability to create one from scratch. But I couldn't join an RP of something that I really have no idea about, no matter how decent the idea appeals to me on the surface - simply because I would be out of my depth in the assumed knowledge on part of the participants.