Here is EPA’s response:
While it is true that contamination can render some materials unfit for recycling (such as food residue on paper products), recycling corporations work hard to find markets for materials that are recycled. With new technology to separate and salvage materials and emerging markets for these materials, recyclers often find it feasible to partner with their end users to identify opportunities for reuse. Some materials will eventually find their way to the landfill or incinerator simply because they should not have been recycled in the first place. Educating consumers about what can and cannot be recycled will help in reducing the amount of materials that eventually must be disposed as waste.