What are signs that a 5 month old Pomeranian is in good health?

I'm going to check out a Pomeranian tomorrow, and I'd like to know some tips on how to make sure the dog is healthy.

Thanks.

The dog should be alert, have clear eyes and fur that is in good shape e.i. no patches missing or dry. I would also look at where the dog is kept. Is it in a worm, dry, clean place?