I've noticed lately that the street spammers are putting their litter around school buildings. They must figure that the parents (soccer moms, etc.) will pick up the kids and thus, see their wonderful signs, advertising everthing from carpet cleaning to weight loss. Needless to say, the signs have been taken down.
My hunt for removing signs seems to be slowing down somewhat. Gone are the days where I would remove 40 - 50 on my tour of the neighborhood. Either the spammers are getting more selective (I only see a handful of signs on the major streets), or they are moving to greener pastures (areas I haven't visited... yet).