Randy Orton: I never liked him really, as he just comes off as the biggest doofus in the ring. BUT at least as a heel he pulled off sneaky bastard quite well and was believable in just being bitter at everything. As a face, well I don't even know WTF his motivation was for ANYTHING
Chris Jericho: I would say minus his 2000-2001 run, because it was quite awesome, Jericho as a face is nothing compared to his Heel phases, especially the feuds he gets involved in. Like he said in his dvd documentary when WCW finally decided to turn him heel after the Lionheart days, "Thank God!!"
Brock Lesnar: The man is a monster, and should be booked like one, and Faces don't become Monsters, the rise up to take down that Monster. Lesnar plays that role to a T and anytime he was made to be the good guy and not destroying everything in his path just seemed way off.
As for faces: I want to have more examples but my mind suddenly went blank.