It's highly unlikely that any club actually ends up covering anywhere near what it really costs to deal with the issues they are responsible for causing. Obviously, violence and disorder tends to be the first thing that comes to mind, but even where this doesn't apply there can still be other costs. Sticking with Pompey, who pays for example for the loss of trade to local business when the whole place grinds to a halt on a saturday due to Fratton Park being in the middle of a small congested city? Absolute mayhem, week in week out. And the fans buying a few greasy burgers here and there comes nowhere close to compensating for it I'm quite sure. And when serious disorder does occur, I wonder how many 'opportunistic' offences occuer in other parts of the affected town, due to there being no police left to deal with anything else?! In fairness though, the 'bussing-in' arrangement does at least provide trade for the local coach firms I suppose!