@Old_Mac_Donald --I am with you —too often in the horse world advice is given that is unappreciated --if the horse owner has asked the OP for help --as in he would like her to show him how to prepare his horse for the ring, all well and good. If it has been a casual remark of, “I wish my horse looked better,” then a reference to Google or a book (“Groom and Win” comes to mind) might be less pedantic.
As to all the “shampoo is bad” posters --I disagree --all things in moderation --don’t know that I’d do a thorough soapy scrub every day, but we showed white (grey) horses at some pretty big venues for years and did thorough nose to hoof shampoo in preparation --we used specific horse products from the draft horse store (same stuff used on the Budweiser Clydes) to achieve glowing white coats and gorgeous tails --expensive, but that stuff worked! (I can’t recall the name, it’s been a while since I bought it). Shampoo with warm water, conditioner, and coat gloss all done the day before, then wrapped horse in a Sleezie, bedded on clean shavings and hoped for the best. Day of show, we did touch ups with Baby Wipes that take the green off hocks (@2DogsFarm can tell you all about green stains on white horses). The white horses may not have been the best in the show, but they were show-stopping shiny and white! As one poster pointed out --it begins with the feed and we fed alfalfa --oh, the other “trick” I heard from a judge who said, “I can tell which horse had a kid (this was 4-H) who brushes his horse once a year, the one that brushes his horse the week before fair, and the one that bushes his horse every day .” Daily brushing makes a beautiful coat!