There are several things you can do to make sure he goes to a good home. First, when you interview someone find out what pets they have now and what they have had in the last few years. What happened to them? Did they get hit by cars? Die of heartworms? Shot by the guy down the road? Or did the last three dogs they had die at the ripe old age of 16? Ask for permission to call their vet to VERIFY this. You can do a home visit to make sure they have a fence, that they will be comfortable with the dog in the house, and that the dog gets along well with their current pets. I would also make sure he is neutered. And I wouldn't give the dog away for free. Even charging $50.00 is better than nothing. Dogs are not cheap, if the new owner cannot afford the cost of an adoption fee, how can he afford to take the dog to the vet when he is sick? Don't be afraid to tell someone "no". If you don't feel good about them then move on! You may want to check with your local lab rescue group. They might could help you place him. Let me know if I can do anything, I will be happy to help if I can.