Aluminum cans are recycled in very large numbers. Pretty much all of them have labels painted on them. Do they have to do a separate step to remove this paint before recycling or does it just burn off at some point? Similarly, if some aluminum foil has contaminates (bits of food stuck to it, for example), does that cause a problem when they recycle?
Along the same line, carbord boxes frequently have tape on them and sometimes things taped to them (e.g. plastic envelopes for invoices or whatever). Does the tape etc cause problems when they recycle them?