Some peanuts have a flaw on one end or one of the peanuts in the shell germinates but the others don’t. These can be eaten after the flawed nut is removed. When peanuts are dried, many of them will shrivel just a bit more than others. They are still edible, but don’t make good seed for planting. Any off type or off shape peanuts can usually be eaten but are best not kept for planting. One other trick I learned is that some peanuts will have 3 nuts in a shell sized for 4. I can pick these out most of the time. I select only the best peanuts that are fully dry, well filled, with solid shells and no sign of damage. These will give nearly 100% germination and are most likely to produce healthy and vigorous plants.
Keep in mind that I grow for seed to be sold commercially. I don’t want to provide peanuts from diseased plants or in any way are anything other than the very best seed possible for me to grow.