The prison officers have assess whether an inmate will cause them problems. A guy can come in with the full intension of behaving but then goes totally crazy. They can kick off, fall out with other inmates, cause jeolousy in others or spread trouble through the jail population. That’s why cleanliness is so important and it doesn’t matter if it comes out the end of a freezing cold hose.
The prison officers don’t have time or inclination to ask him a load of intimate questions. They suspect he’s gone jail bent and that’s all that’s needed before a mandatory visit to Mr Hose. It’s freezing cold water for this chap, underneath his foreskin and right up his hairy arsehole. They want him spotless.