The people that posted these will NEVER take them down. That's called advertising- the more people that see the message, the more business they think it would bring. As a community 'cleaner upper' , I used to walk around with shopping bag in hand, removing those signs (when the price was $16), but gave up. I think the only way to discourage this activity, is for the sanitation dept. or police to actually issue tickets to the companies involved.