Good seeds are brown and meaty!

A good way to check and see if your seeds are good, is to roll them between your thumb and index finger. Apply a very small amount of pressure over time, but not enough to break them. (they can usually take abuse, but don't test your luck) If you hear any crackling whatsoever, toss it.

I toss all of the seeds I don't want into a tin and make cannabutter with them.