People Who Spit Everywhere And Generally Lack Respect For Others

I've never understood people who insist on spitting everywhere. My neighbour does so, in the stair, in the lift...anywhere! I wouldn't mind so much but i recently came out of my flat a little while after hearing him at my door and saw a big spit pile right at my door and since he spits everywhere plus no one else had been at my door that day, I knew right away it was him.
As soon as I saw him I pulled him up for spitting at my door and he said sorry, but a few days later I left my flat to find not only someone's disgusting spit at my door, but they had done so twice! And again, he was the only person I' heard at my door that day, plus the only one I know disgusting enough to do something like that.
However this time when I pulled him up for it he got huffy and said it wasn't him but I know it was him an that he was most likely denying it because his dad was with him and would have moaned at him if he'd admitted to spitting right in front of my door, or possibly just because I'd already pulled him up for it once and he didn't want to admit to doing the same thing again after I'd told him not to do it because it was disgusting.
Either way, there's no need in such behaviour, especially considering he's in his 20's (23 I think) and should know better, especially after me previously telling him to stop it. It's disgusting enough seeing children spitting out in the street but an adult doing it inside a block of flats is just ridiculous...especially doing it right at my door when he only ever comes to my door when he wants me to do something for him! Even if he didn't only come to my door wanting a favour it would still be ridiculous that he spits right in front of my door!
So to anyone else who thinks its ok to behave in such a way...I don't care what anyone has to say about the following comment ( although I'd hope most people would agree with me on this) - YOU ARE DISGUSTING!  If you really feel the need to spit, do it in the toilet, or if you're not at home or in someone's house do it outside, preferably in a place where no one else will see it and be disgusted by it! Seeing someone's spit is always disgusting, whether it's outside (which in my experience tends to be most often at a bus stop) or anywhere else, but seriously, spitting inside a block of flats is beyond disgusting and right in front of someone's door (especially when you're at their door to sk them to do something for you) just completely and utterly takes the piss!
For anyone that applies to- you need to learn what's considered acceptable behaviour before you leave your house in future. If I hadn't been raised to respect other people and other people's property I'd seriously be tempted to spit right outside my neighbours door several times for each time he did it to me, but my mother raised me to be respectful to others, which obviously I'm thankful for, but at it really annoys me that being respectful means I have to just take this kind of crap from other people and can't do anything about it unless I'm willing to sink to their level, which I'm not.
So for now all I can do is hope people with such disgusting habits and lack of respect for others will learn to change their ways but unfortunately it doesn't look like that's going to happen any time soon =(