Neighbors with little kids should be a perfect match when you've got kids the same age. Well, what if the kids are unruly hooligans that rub off on your little ones every time they're together? Not a good situation, nor is the sticky one you find yourself in when you don't want your kids playing with neighborhood kids. Although this is tough, you can finesse your way through it to set the limits for your family.
Decline a play date invitation politely. Leave out the excuses or details, though. It's not necessary to say why your kid can't play. For example, when asked to play, you might just say, "Oh, sorry. We aren't available then." If you hear something more vague like, "We should get the kids together next week," feel out the situation. You may be able to put off the neighbor with a comment about having a crazy week coming up.
Keep declining in the same way every time you receive an invitation. With repetition, your neighbors will hopefully get the idea that a play date relationship isn't happening.
Give your neighbor a little more information if the invitations keep coming and things are getting a little tense. You might have to be more direct, bite the bullet and say something like, "I'm sorry. It doesn't seem like Jeremy and Ryan have that much in common. Maybe when they get a little older we can try again."
Talk to your little tyke if she wants to go play with the neighbor or she wants to invite the neighbor over to play. Be honest, but keep your explanation simple. Say something like, "I know you'd like to play with Samantha, and I wish I could let you. However, I don't feel comfortable with some ways Samantha's mommy and daddy are taking care of her. I'm afraid it's not a good idea to spend time playing with her right now. Maybe when you girls get a little older, it will be different."