I have a tank bra on my 09 red, I take it of every time I wash the bike and polish the tank. I usually waash the bike after every ride so there is no time for anything to build up underneath it.
Your friend should have looked under the bra before he bought the bike. Would you buy a car with a blanket thrown the seat without looking at the seat? 
He's not mad at the PO, he's po'd at the crappy Tank Bra that scuffed up the paint it was designed to protect. If you have to take it off every time you ride the bike --- WTF is it good for? My Tankslapper has been on my tank for 3 years and I have never needed to take it off and wax underneath it. You can tell there is no dirt under the film because you would see it. I went ahead an peeled off one side to show my buddy how good it works --- Guess what? PERFECT paint right where my knee rubs the tank and I have a RoadCrafter suit that is like sandpaper. Film is scuffed, but not the tank.
Tank Bras SUCK and are a rip-off. Typical POS farkle for the idiot masses. And he can't "rub" out the paint, it's black and too scruffed for help. Yeah, he should have looked, but he was dumb too for trusting that a Tank Bra PROTECTS !!!!!!!!
