Look Out for Foggy or Nonfunctioning Windows
Foggy windows are easy to spot, but they can be a big problem. Look for condensation and water in between double-paned windows. That's a sign the seals around the window's edges aren't working and water vapor is seeping in.
Make sure the windows are functional -- yes, all of them. Newer, inexpensive windows often stop working even after light use, while older windows could be painted or warped shut. You'll kick yourself later if you buy a home with faulty windows just because you didn't use a little muscle.