One of the theories I've always had about passing the guard is that one way to be consistently successful as a guard passer is to always pass the guard you want - not the guard the guy on the bottom wants.
An example of this, I think, is GSP's habit of passing to his right. This forces guys to play guard off their left hip, which tends to be most grappler's worst side. It's not 100%. But I suspect it is an edge.
We hear about this in basketball and soccer all the time - the idea of "force him left" - make him rely on his weaker side.
I think part of what works in the BJ Penn passes I posted earlier comes from BJ forcing guys to play butterfly guard - or variations off it - and then exploiting the fact that a good butterfly guard pass will beat most people's butterfly guard most of the time simply because very, very few grapplers have butterfly guards that are anywhere near as advanced as the rest of their guard game.
That's not to take anything away from BJ's guard passing. But I wonder if BJ and I are on the same page on this. If you read his books, then you realize that BJ Penn has an exceptionally practical jiu jitsu (witness his readiness to stand up from guard rather than insisting on fighting from the bottom). And the idea of forcing your opponent (or goading or tempting or tricking) into fighting from a position that is a weaker one for him/her and a stronger one for you is practicality personified.
