First of all, I will say that I like Fouling. Playing Chaos Dwarves, I like to clean the pitch. But I also like scoring : using my hobboes and my Bull Centaurs for offense is my main goal in the game, just to reassure Marcus

I have one player with Dirty Player on the team, and I would be willing to make it less effective, but you have to give me something in exchange, and I mean SPP's !!!
I like Manusate's idea to make DP players more sneaky. Maybe they could be sent off only on 1/6 chances when the referee has his eye on you and not seen at all in other occasions (but still drawing the attention to your side) ? That would add nice flavor to the skill.
Remco's remark is also great. I wouldn't mind having my sent off players penalizing my team of one less player on the pitch.
Vorner23 adds that it might be too easy with a +2. OK, transform this +2 on either armor or injury into a +1 to armor AND +1 to injury.
Zombie is right when he tells that major North American sports allow the coach to field players to replace the penalized ones. But don't forget that when you get too many personnal fouls in a Basketball match, the opposing team gets free throws; that hockey players sent off for intentionally hurting another get a suspension (not as harsh as it could, but this is another debate

So, finally, I don't mind the Fouling to be well-structured by strict rules, but my final opinion is that if you can get penalized, you should get a reward (SPP) when it's "well" done. I would even accept 1 SPP for fouling casualties, you see how docile I can be !

Fred
Sorry for the long post...