Keep in mind, a lot of frozen rodents have bedding dirt on them from the facility they came from. I just soak them in warm water and rinse them off before feeding. Many BPs prefer wet rats anyway lol.

Plus many rats can get rodent mites or wood mites. Neither of which are harmful to a snake that eats them. Especially after they have been frozen.

A magnifying glass will help you see if the specks have legs. Then you can judge if you think they are safe to feed.