I know they’re absolutely filthy because of how black the water is when it’s rained onto them and some of it’s gotten on the windowsill. Don’t think mine have been cleaned in years and I’m not about to bother doing it now. I hate the job. It’s fiddly and without a movable shower head it’s really tedious. I won’t do it until summer if at all.

My mum lives on the ground floor of a whole bunch of apartments in Asia and she’s directly opposite a multistorey open air carpark. She needs to wash her fly screens once a month at least and they are always black. The previous owners just closed the windows and used the air conditioning all the time.