His first chance came against Dan Henderson at UFC 100, but he was rendered unconscious by an incoming "H-Bomb" and sent to the back of the line. He was able to re-climb the 185-pound ladder and once again needed one big win to earn his crack at the crown.
Then Chael Sonnen defeated him at UFC on FOX 2.
Last but certainly not least, "The Count" went for his third attempt at UFC on FX 7 last month in Sao Paulo, Brazil, and was put on his ass by a Vitor Belfort head kick (watch it here), removing him from the middleweight title picture for the foreseeable future.
What do Henderson, Sonnen and Belfort all have in common (aside from getting finished by "The Spider")?
They all compete with a prescription for Testosterone Replacement Therapy (TRT), which Quinton Jackson (also a user) said "immediately changed him" for the better after a few small doses. True, he missed weight and lost to Ryan Bader in Japan, but at least he was having sex five times a night.
The treatment is a performance enhancing drug (PED), I don't think that's debatable. If it wasn't, then no one would take it. As of now, it's legal with a doctor's prescription, so the debate becomes about necessity. Nate Marquardt and Antonio Silva both claimed they needed it to keep their jobs.
Then they went off the stuff.
Post-TRT, "The Great" managed to defeat Tyron Woodley for the Strikeforce welterweight title. Once "Bigfoot" gave up the treatment, he crushed Fedor Emelianenko in the promotion's heavyweight grand prix. Frank Mir jumped on the TRT bandwagon and still got turned inside out by Junior dos Santos.
What does all that mean?
Unfortunately, we don't know conclusively. What we do know, is that long before Bisping ever fought "The Phenom," he (just like Jon Jones) called TRT "dressed-up cheating." Looking at his history of defeats in the big spot, it's hard to imagine him changing his tune.