Explain to him that the shit that he does needs to stop. Explain to him that you have been more then a respectful neighbor and he should do the same. If he refuses to listen, then honestly use to wrongs to make your right. Do all the shit that he does back to him. Next time he piles up the dog shit, go out and move it on his front porch or something. As for the snow thing, it may take work but, shovel your yard and pile up the snow around his car.
I'm all for being reasonable but some people are just assholes. Calling the cops won't do shit but waste the police officers time and then probably make your neighbor want to be even more of an asshole towards you.
Although next time they fuck in their hottub you could probably call the police for that. If you really wanted you could be evil and add in some lies.
"Well officer, I heard noises but figured they were horsing around, until my 'little niece' came to me and told me she saw a man hurting a woman. When I went to look I realized my 'little niece' witness them commencing in sexual acts. Lawdy lawdy I even saw them get their dog involved"
Fuck people...seriously. Or you could pull a Dennis, somehow smooth talk your way into his girlfriends vagina, tape it, show him and make him feel like the pathetic prick I'm assuming he is. Or even pull a Me, Myself, and Irene and just shit on their front lawn...