You ask, we answer

George asks: Most oil and hazardous liquids come in a number 2 plastic bottle. These are things a homeowner would have a lot of, like, oil, antifreeze, weed killer or dozens of other products that come in these containers. If the bottles are washed out, can they be recycled and if not why?

George: You raise a good point, but the situation you describe is not unlike our experience with another recyclable material, namely cardboard. Pizza comes in cardboard boxes, and there was a time when we said pizza boxes were acceptable if they were clean. We soon found out that different people had different definitions of "clean," and soon we were getting pizza boxes that were greasy or had cheese stuck to them, and before long it was just easier to not accept pizza boxes at all.

The point here, and we do have one (apologies to Ellen DeGeneres), is that it's easier to just ask people to bring these materials to a hazardous-waste collection, ensuring the contents will be safely disposed of.