They are going to let me know by tonight if they want to adopt him. This way, you can nonconfrontationally part with these people who would not provide a good home for your pet. You should deliver the animal on the next day off for the people adopting the animal so that they can spend all day with the pet. When you arrive at the new home, you can still back out if you feel that for some reason you aren't comfortable leaving the animal. You can always say you decided you couldn't part with the pet.
Some people even go so far as to interview neighbors.
Rely on your instinct. Cats and dogs are completely at our mercy. If you are parting with your pet or an animal you have found, please extend a simply act of mercy by trying to find the best home possible for this innocent being who trusts you. When we at PAL place pets, we screen people thoroughly, charge them for the pet, have them sign a contract, and do a follow-up visit. The truly responsible people not only agree to all this, they will often thank us for being so careful.