I have noticed random bits of hose without proper fittings before I think for example in India and just assumed they are for use by the cleaners or for filling the water jug in squat toilets.
But Now I'm travelling in Malaysia and Singapore and there are more western toilets than squat toilets in the places I've been yet proper hoses with proper fittings are very common in toilets:
(Hose next to a Western style toilet in my hostel in Chinatown, Kuala Lumpur.)
At one place in Singapore there were even signs on each cubicle door stating whether it contained a western or squat toilet, but also whether there was a hose! (I didn't take a photo of the sign, unfortunately)
This makes me think there is a use for the hose for clients, not just cleaners. But for what purpose? Should I know how to use it as a tourist? Please tell me it's not a kind of alternative to a bidet!
Possibly related is the fact that many toilet floors are awash with water. This can be a big problem if you're not wearing waterproof shoes or have to lower your trousers and keep them dry. Other than this toilets are pretty clean and I've seen both the hoses and the wetness in what I would regard as somewhat "fancy" places.