Strip wash, and the bits you can't reach, oh well.
They're usually the bits that don't really sweat much anyway tbh.
I went for YEARS without an accessible bathroom, and the effort required, and the getting wet and cold (no heating upstairs) also had to be considered.
Didn't wash my (admittedly stupidly long) hair for well over a year, because the position I had to get into to wash it over a basin was incredibly painful.
You may find it horrific to think of not being able to hop in the shower twice a day or luxuriate in a hot bath, but there are plenty of people out there who cannot.
Even with an accessible bathroom, with my disabilities and chronic health issues, I often have days where it is a choice between work and earn a living (from home, no one else is subjected to my stench) or, shower and get clean and then get warm and then go back to bed to recover.
I don't really go out, because to go out I would want a shower first. But to shower first means a good four or five hours to wash, dry and then rest. It's a lot of effort if it's not absolutely vital. It totally rules out early morning appointments.
I am trying to get adult social care out to my Dad, he has no water! He gets big bottles/water containers from either my sister or the pub, and uses that to flush the loo and drink coffee and wash up.
He bathes when she manages to drag him kicking and screaming (pretty much literally) round to hers and stuffs him in her bath, but since she's been recovering (sadly not really, shes now worse than pre surgery) from heart surgery that has gone by the way-side as she's really not well enough.
There is only so hard we can push him (And i can't at all, he won't talk to me on the phone more than a couple of grunts that he's old and tired and then hangs up), if my sister pushes him to try and sort things in person, like tidying up, washing etc... he's just vile to her and then throws her out of the house. He may be 83, but he has the strength of a bloody bull.
So theres a lot of people out there, between the disabled and the elderly, and those living in abject poverty, in poorly maintained homes etc... who are not able to wash properly, or bathe or shower.