It cracks me up when ppl ask if you really use them? You have no choice! As he correctly states every 5 pulls! I would prefer a seperate switch myself always come on on my clean car! ARGH!!!!!
Yes, they always know when you've just washed the car

No choice (unless you disable) but presumably there are some people out there that value them as a aid to cleaning. Maybe people that don't clean their cars very often?
A seperate switch would be better than the current auto setup with the wiper stalk, but I can't think of any time I would choose to activate them, but then my lights get washed weekly/fortnightly along with rest of car so headlight washers are of no benefit.