However meticulous you are about washing recycling still enough organic material might be left for a fly to consider it a viable site to lay eggs. Also washing can sometimes work against you because putting things in the recycling wet can allow a licour to form over time that will smell as bad as anything you have smelled. Wash and disinfect the bins and in the hottest months put them outside. Do you note there is a limited age distribution in the fly populations you see, they are all young adults and all clean and shiny as if they have never been outside.