Some people say that cheating has ruined football. I maintain that 'cheating' has always been in the game, but the main difference between 'then' (to be honest I'm only talking as far back as the 90s) and 'now' is that back then it was an honest kind of cheating, whereas now it is pure deceit.
Back in the day, if Roy Keane had a problem with a player, he would just hit him with a massive tackle, which might constitute a foul. Technically a foul is 'cheating' - the difference is, he wouldn't try to hide it. He would tackle hard and if the referee thought it was a foul/booking/straight red (let's face it, Keano was no stranger to the straight red), that's what he got and he accepted it.
These days footballers try to gain an advantage by deceiving the referee - diving, making an absolute meal of contact equivalent to a stiff breeze, trying to get players sent off etc.
So my controversial opinion is that 'cheating' has not ruined football, it's more a change in the nature and level of cheating that poisoned the game.