when i fill a shallow sing hole with putty - the red bondo glazing and spot putty - then after thats dry i sand, then put some mr. surfacer 500 over that, then sand it off, then i spray a light primer over it, everytime i can still see the mark. like it didnt completely fill it in. what am i doing wrong here?

try over filling the hole-then dont sand too much - sometimes feel is beeter than sight to tell it it's flush- fill sand prime -repeat the litany of the model builder- it's kinda like a rosary -lol

I used to have the same problem. Then a friend had me try this method. Once the putty had dried and was sanded, I would take a small drop of CA (superglue) and put it on the puttied area. Then quickly wipe it away with my finger and then let it dry completely. A little light sanding to blend everything back in and the marks were no longer visable when painted. Johns suggestion is also a good one and a little simpler to boot, but at least this way you have more than one option open to you. "Q"