Lol I talked to my brother about "bad" neighbors and he said I'd be selfish if I don't help them. "The game is free you don't spend money unless you want to. You're helped when you're new player so help others!"
I couldn't act differently after that conversation so I always help and gift but I rarely tip!
Making things clear is the most important thing if you're still not happy with the amount of neighbors you have or the way they play