I work in the waste hauling industry. At our recycling collection/sorting facilities, the recyclables are sorted by hand on a conveyor belt. If they're in a plastic bag, they get thrown out. Too dangerous to have guys try to open plastic bags with who-knows-what in there. If there's some pasta sauce still in that glass bottle? Thrown out. A little bit of grease on the pizza box? Thrown out.
The vast amount of recycled stuff gets thrown out. The key is to make sure everything you recycle is completely clean, and isn't in the plastic bag.