Going to the dogs, eh'.
I'll have you know that I practice good hygene and also social practices (for Australian social situations).
For all of the years of catching public transport I have seen many things. People drinking alcohol, sniffing paint (sprayed into Coke containers), sleeping (sometimes with a bit of drool, yes), singing, kissing (french style with lot 'o' tongue, bleh) but have not yet seen someone spit. Especially in a bus.
I assume this is not a result of people spitting, but a result of Krudd's speach to everyone to keep clean etc... and all of the money spent for advertising as a result. Therefore, this is part of the money spent rather than as a result of people being unclean asshats. Most likely at least.