We donít have any blinds, only curtains. I never clean them, Sorry, Iíve had the patterned living rooms ones dry cleaned twice, but itís a real hassle getting them down from the curtain rod & hanging them up again! The 3 lots of bedroom curtains Iím sorry to say, have never been cleaned since we hung them up in June í79 but no, they donít look dirty.
I have timber venetian blinds and some curtains. Both are due to be done. The curtains are washed as needed, probably every 8- 10 months. The blinds get a swipe with the duster or damp cloth whenever there is something to see on them but get taken down, disassembled and given a proper wash twice a year.