This might be a little late, but a good product to use for filling pin holes is called "Icing" available at most paint jobbers. It's a 2 part polyester putty that fills pin holes, and is also used as a final skim coat over a filler repair. It's about the consistancy of halfway between bondo, and primer/surfacer. And is very easy to sand, unlike a lot of other polyester putties. A lot of the time this is all I use prior to a primer/surfacer as I'd rather fix the dent, and use a bare minimum of filler.
