Somebody hasn't been paying attention.

Geek,
If you are going to paint them you can use the balsa filler or Bondo. The balsa filler gets really hard once you paint it. It's been a while since I did mine but I'm pretty sure that's what I did. Dust them with the color you are going to use and sand to find the low spots. After they are filled you should use primer. Be patient (shouldn't be hard after using alphatic on the model) and only spray a little at a time to avoid runs.