I guess I'm the mean one in the bunch, I spray them in the face. It doesn't begin with accepting water to the face, but respecting your hand to keep their head down. Basic manners are a must, I then start with keeping my hand on the noseband of the halter, I start on the forehead, work around the eyes, along the pole on the cheeks, and under the face. I'm always very careful not to get it in their ears. It doesn't take long at all to get into this daily routine, and usually after a week or so, I can rinse their face without any halter at all, just a hand over their nose and they drop their head to my waist level to get it rinsed off. I don't do a trickle of water either.
I know it sounds mean, but where I live, if they have sweaty faces day after day, I will get serious skin conditions. They all get rinsed off daily, they stand without a halter and drop their head to get it rinsed without a halter. A simple trickle or a wet rag or sponge would never get the deep down sweat. None of my horses mind this. I started using this method that I learned at a show barn that I worked at as a teenager. A lot of the horses actually enjoy it. My 4 yr old has had it done this way since she was 6 months. She loves to stick her face in a running hose.