And 9 times out of 10, this is the result of using the rear window defroster. Some people get lucky and it doesn't bother the tint, others get bubbles from it heating up the adhessive. Or the person putting it in didn't have much practice doing it. The way I feel, if you don't want to learn how tto do it, take it to a shop. If you want to save yourself some money, practice on your own. Everyone has their own personnal preferance. Like Dee said, do you take your car to the shop to get all your mods put on.