I have the walmart tint on my front signals, and it has stayed on ok ever since November.

I used to have spray tint on there before and yes, over time they did pit. I had to replace them when I got a rock through them.

The finish is still smooth on the walmart tinted lenses, and there are no pits either. Since the tint film is a little thick, it seems to offer some protection to the lense.

If the finish ever dulls or becomes worn, I'll just cut some new film and re-apply. Even better, a roll of the film is less than $3.00.