I parked under a tree a few days ago so of some birds decided to deposit some poop on my bumper. It was on the area covered by the clear bra. When I was about to wipe it off, I didn't wait long enough for the quick detailer to soak through. So the solid particles left some scuff marks on the film. But fortunately, I buffed it out with some plastic polish.

So my advice is, treat the film like paint.

 

the film will swirl even if you just touch it with your fingers.