I'd agree that it decreases the amount of litter you see, but more from the point of view that tramps/poor people go around collecting them because they can make a few quid. People will still chuck a can on the floor rather than carrying it around so they can get 10p back.
1. As b points out, homelessers will be inclined to pick up the chavlitter to exchange for Red Stripe.
2. Still with the yellow bile, I see? You care nothing for the lives of Australian cricketers or our watery chums? I believe there is a term for those who exhibit a lack of empathy.
Yes, you're a psycho.