If your car has a substantial amount of mud, dirt, sand, and dust, that has caked on or has accumulated over time, a car wash without water isn’t advisable. Because merely wiping them with a waterless wash would result in scratches on the paintwork.
Yeah it's not advisable if it's that bad. Some still do though.
Testing the LIMITS of Optimum NO-RINSE! �� - YouTube
I've used ONR, GG and Ech20. I like them all. They all worked well for me. Ech20 leaves a nice gloss behind. I had no streaking issues with it used as a RW and WW. It's supposed to haze up, then one final pass it is easily removed.