system
Given the following post, respond as if you're commenting on Reddit:
human
How much cleaning is enough when preparing recyclables?

I'm concerned about the cost of wasting water and using soap versus the needs of properly cleaning recyclables.  When cleaning empty bottles of vegetable oil, as an example, when is the remaining oil or soap residue no longer a concern?
gpt
Cleaning recyclables is really only for household hygiene and to minimize insect and other animals from getting into your bins, making a mess, and on a macro scale, of attracting them at all.  This applies to the recyclables sorters and processors, minimizing smells, bacteria and vermin.

Plastics are sorted, compacted and sent to a processor where they are chopped up and washed (sometimes, not all do this depending on who's buying).  It varies by processor, but often the wash is a high temperature detergent similar to an automatic dishwasher.  This is required because food oils can degrade some plastics or foul machinery during the remelt processing.  After that depends on market conditions in your area or country.  Generally, the clean chop is sent to a processor for melting and pelletizing into proper form for other plastics molding machinery.

Metals are compacted and sold to a processor that melts it and pours ingots of steel or aluminum.  Glass is sorted into clear or tinted, and remelted.  Of course, the temperatures to melt glass or metals are irrelevant to any food contaminant on the original recyclables.