I'm kind of bummed out that the Mashburn thing on IMDB was a trick. It would have been a complete shock to me if it was him and it would fit so well in so many ways.

First and foremost the fact he slept with Lisbon shows just how persuasive and charming he is that even being a cop looking for RJ none of her instincts clued her in.

He posseses all the traits of narcissism you'd expect from the RJ character and he never hid any of those traits but instead flaunts them unlike characters like Haffner or Bertram who come across as morons or incompetents (obviously an act if RJ but still, it'd be nice if RJ DIDN'T hide who he was but instead was on fully display in plain sight)

"He is Mar" could be he is Mashburn (sort of, lol.)

He's been in the show since the 2nd season. It's too bad it's not him, lol!!