The vinegar in warm water is excellent - why didn't I think of that
I only shampoo three of my horses 3 - 4 times through the season but I cold hose them down and take a brush to the yuk every night they come in a sweaty mess.
The fourth horse has environmental allergies and gets shampooed 1 - 2 times monthly with a prescription shampoo.
When I give them the final rinse, I use my finger nailes to lightly scratch/massage any excess dirt and sweat the brush missed; generally along the top line and the butt and a favorite "itchy" spot whether they have dirt there or not
I never have been a fan of sponges. For the face and personal areas, I prefer those big white wash cloths that come in a pack of six (or maybe it's eight) at WalMart. They are good and sturdy, wash up in the washer very well and best of all they are really cheap so if you ruin one you don't feel bad. I've got two packs I bought two years ago and they're all still washing four horses
I soak the wash clothes with enough water to rub & squeeze it down their face, yet they don't get the sensation they are bleeding or drowning. They all put their nose to my chest while I "massage" their face with the wet wash cloth and I am careful to avoid letting water drip into their eyes or noses.
While I have both the shower-type nozzle and the old, dependable, brass nozzle that turns to adjust it, I prefer the brass nozzle because I can hold it and adjust it, all at the same time I'm brushing with the other hand.
I have one inch water hoses, we have a lot of water pressure and it's just easier on my arthritic hands to use the old fashioned nozzle.