While Roy Keane's name might quickly come to mind, not many people would think of Manchester United as a dirty team.
And in recent years it seems likely that Sir Alex Ferguson has acted where necessary to nip any risks in the bud.
Take Wayne Rooney as an example.
Much of the talk before the England vs. Montenegro match this week was about the England striker having to remain calm.
Wholly superfluous of course and much of it by the Montenegrins, because all you have to do is look at Rooney's recent disciplinary record to see he is a reformed character.
Sir Alex surely had a hand in that change, as he did to stop players like Ashley Young from diving.
Now that prompts a fundamental question: How do you define a dirty player?
If you do it based on yellow and red cards, then you may pick up players like Luis Suarez who has been booked for diving.
Basing it on who commits the dirtiest fouls is far more subjective, of course. Yes, you can see nasty tackles even though referees don't always spot them. If they result in a red card, then there is a record to refer to.
Otherwise the best objective measures we have are those counting the number of fouls given and the number of cautions.
So plenty of you will have an opinion on who the dirtiest players are because you can all recall one or more seriously bad or dangerous tackles. Like the one on Nani that Jamie Carragher got away with.
In the slides that follow, we shall necessarily have to mix the subjective with statistics, because we don't have the figures to validate arguments about some of the more obvious players from the past.
In any case, the question "who are Manchester United's dirtiest players of all time?" is ultimately a matter of opinion. See what you think.