Adult fleas spend most of their time on your pet.  If your pet has fleas, they will be easy to find and they will leave little black specks on your pet.  These specks are flea poop!    

--- If you think they are dirt. . . Remove those little black specks from your pet’s skin or hair and place on white tissue paper.  Add a few drops of water. If the tissue turns red under those little specks then your pet has fleas, because you have just constituted dried blood. ---

Below the life cycle of flea.