I found this out the hard way. My car is only a couple of months old and I keep it spotless. I washed the car, used Optimum Mineral Deposit Remover on every surface, especially the glass, washed the car again with Optimum No Rinse, clayed every glass surface using ONR again, thoroughly dried the glass with 365 gsm edgeless microfiber towels, then when I was making a final pass using dedicated microfiber glass towels with glass cleaner, I must have picked up some minute particles near the rubber seal on the rear passenger side window. I pushed too hard and noticed faint vertical, then horizontal scratches. No one but me is going to notice this, but it just pissed me off after all that work trying to achieve perfection before applying Aquapel.
