i know you have had lots of responses but let me add another. sorry it will be long..
we moved into a house and there was a boy next door one yr older than our oldest. wow-- we were so stoked. the parents were church going bible class having parents of the block. what more could you ask?
time told us alot. this child was horrid. i too had to restrict playing to only my house and constantly correcting this child. we would do this awhile then try again with my boys going over there.
it got so bad sometimes my oldest would get his younger brother and come home because this neighbor liked to pick on the younger one or act inappropriate and my older one knew better.
(we are talking preschool to 3rd grade ages here not teens)
the finaly straw was when they were 9 or so and i heard this boy telling my son that he had purposely distroyed some toys of his and his sisters with gardening sheers. how his dad had been so upset and punished him by grounding him for the week. as i listened i came to know that it had happened just that morning. here he was at my house that afternoon. he is laughing and telling my son how he got away with this premeditated distruction AND how his dad was basicly lame because he also got out of punishment.
at that point i told him i thought it was time for him to go home. he had no idea why. i informed my son of my thoughts on the matter and that there would be no more contact with this boy.
during the couple of yrs this all built up-the couple - more so the husband- were shown more in their true light because we actually were a good parent couple and family and they more pretended. they were no longer the best on the block.
the father came over after a couple of days and asked what was up. why i had told his son the past couple of days that my boys could not play with his son. so i flat told him. i dont approve of his behavior and im done having my kids being exposed to it. so dad says- so you're saying that my son is a bad influence and i replied straight up.. "yes"
the dad was all like- just because he was being a boy and i punished him for that. so you dont think i punished him enough? and i told him, its not that I dont think he was punished enough... HE KNOWS he wasnt punished enough. he said so himself.
although that was the end of that... this man still caused trouble in our lives. he didnt like being shown up. it got into having the cops called every time our dogs barked. but i got with the cops and told them what had transpired and they gave me tips on how to handle it and it all worked out and backfired on him and never heard a word again.
i say- talk to the parents. dont just present them with a problem and blame. let them know you have a problem not them. and you are looking for a solution and would like their help. make it like you are asking them to be on your team to help your son not develop these habits. they KNOW if their son or nephews and nieces are teaching him these things.
by letting them know in the manner that you are aware they will have to pony up and stop it or become part of the problem that you may just have to remove your child and your family from.
it IS possible to live next door and not communicate. i know its not how anyone wants to live but always put your child and your family first.
my boys are 19 and 21 and i have never been more happy about a decision i made in their lives than that one. and yes- they knew exactly what and how it all went down.
good luck :)