[dmforcier]

No, unripe pods will have ripe seeds in them. Just fewer than ripe pods. Look at green jalapeños from the store. Lots of mature and viable seeds. However, different varieties have different treasures inside, and some are really miserly with the seeds. Some, notably C.pubescens, hate me and I won't try to give advice for them. But by and large I do what you do - seed a pod, dry the seeds, put in a bag and label the treasure.

Your instincts are good with the white seeds. (Except for C.pubescens which has black seeds.) Look for larger, off-white, plump seeds. If you're seeing off-color seeds then suspect that fungus has gotten in among them. This doesn't mean that the seeds won't germinate, but best to use the healthiest ones you have. Molding pods are still usable to some degree, but undesirable.

CR, are you dealing with large quantities?