Invariably, they will toss the butt out the window. They all sincerely believe that cigarettes are biodegradable. As far as the number of items, cigarette butts probably outnumber all other litter combined by at least a hundred to one. Look around the ground where the smokers at work spend their breaks. Lots of butts ground into the pavement, burn marks on the walls, and butts on the ground.
Smokers are rude.
They really think that what they do is a private matter. They don't believe cancer will affect them and they don't believe it will affect others. Their cars and homes have burn marks on the carpeting and they don't think it is a big deal if they burn something you have. If you're smart, you won't allow anyone to smoke in your home, and you won't put up with it anywhere smoking isn't allowed. Smokers have clouded reasoning abilities.