Yeah I learned this the hard way when I was adjusting the door window in my Challenger, about half of the holes were washed out and the screws would not bite. Since they are a unique screw, I didn't just want to jam some next size screws in there, so after looking at it and realizing that unlike a normal round hole the slots tend to migrate inward I thought I'd try the welder clamps to see if I could fix them. It worked in probably 95% of the cases, there were 2 holes that could not be saved which I had to weld up (not fun on a painted car). The real long clamps worked pretty well. In some cases you can get a small hammer or other heavy instrument to beat it back.
The real key here is DO NOT OVER TIGHTEN the screws, they do not need 50 ft lbs, more like 3 which isn't much.
One other thing, I have found a local hardware store that carries a wide variety of stainless sheet metal screws (different sizes, lengths and head styles). I keep pretty much a box of each type (within reason) just in case, it has come in handy. The factory screws are chrome plated I believe, I really like the stainless better (not truly 100% stainless as a magnet will pick them up).
