I agree & disagree with Xavier.
Flashbangs shouldn't be disabled since it's part of the game, and once used correctly it's very useful. I understand it's frustrating sometimes when your teammate accidentally throws the flashbang against a wall, blinding everybody except for the enemy. I've been there, I even said in the server:"People here throw flashbangs as if it were rice at a wedding". My screen was white 3/4 of the time playing there. Although I get your frustration, I don't think it should be disabled or limited. Having only 1 flashbang will restrict you to a certain point. Especially if the T's are trying to arm the bomb, you can flash them and run in and get the kills easier. It however would be good if people would actually THINK before using their flashbangs. Think in advance, "I might need this last flashbang later on. I better not waste it on a random throw above A".
So, my advise is to use your flashbangs tactically/carefully. What goes for your teammates, try to avoid the teamflashes. Or try to guide your team. "You there, flash A!" "I NEED A FLASH IN TUNNELS!" for example. This might cut down the random flashes everywhere.