Since I began following college football, the following summarizes the USC head coaches:
McKay -- proven cheater, won national titles
Robinson (1) -- proven cheater, won national title
Tollner -- never accused of wrongdoing, no titles
Smith -- see Tollner
Robinson (2) -- brought back as coach but told must follow rules this time, no titles
Hackett -- see Tollner
Carroll -- ran most scandal-ridden program of the decade, won titles
So conclusion #1 is that if SC cheats, blatently and consistently, they win. If they don't, they don't.
Next is analysis of how the cheaters did in the pros.
McKay -- went to NFL where you can't buy the players and through dubious means keep them eligible while your peers do not, set record for most consecutive losses, overall lost 2/3 of his games (first couple years can be blamed on expansion, but not thereafter)
Robinson -- went to NFL's Rams and after early success but no Super Bowl appearances, the team collapsed and couldn't fill the stadium, and soon after his firing the franchise was moved to St. Louis
Carroll -- TBD, but note that when he was in the NFL previously, he had a losing record, which he does have excuses for.
So conclusion #2 is that if SC coaches are deprived of their ability to cheat, they don't do very well.
So SC needs to choose between being clean and at best moderately successful, or being filthy and winning some BCS championships. And Seattle should be thinking about who it will be hiring as its new head coach in 2014.