I have a navy show coat that just seems to be a dirt magnet. Dust shows up brilliantly on it. I can’t figure out how to keep the dang thing clean.
Can I put Scotch Guard on the coat? Will that ruin it? 
What fabric? If it’s a wool blend you can often rub fabric to fabric to get rid of most stains. Many coats today are actually washable gentle cold non chlorine detergent hang dry. I would not scotch guard most fabrics for dust. Just shake it out
I have a Grand Prix jacket in the stretchy technical material and it IS a dirt magnet so I just have to wash it lots. I haven’t found a better solution as wiping it off with a damp towel just seems to spread the dirt. Interested to hear if others have better solutions.
I learned this years ago to keep my wool show coat clean… wet a washcloth with warm water and wipe off any scrunge or slobber, then throw the coat, washcloth and a dryer sheet in the dryer for about 15 mins. Voila! The coat comes out hair and dust free with no nasty chemicals!
I would get a lint brush or clothes brush and brush your coat off regularly. When it does get dirty and if it’s not washable there is a product called S-32. It comes in a big yellow and brown, 16 oz bottle. I think it may just be dry cleaning fluid? We use it all the time. You can also get a Dryel dry cleaning kit you can use at home.
Our groom taught me an awesome trick last week for last minute cleaning…he sprayed show sheen on a clean rag and wiped a few dried slobber spots off my sleeve. Looked great!
Don’t put it on until the last minute
wrap yourself in plastic
have a groom so you never actually touch your horse except when you are on it
have two or twenty coats
do jumpers
IMPOSSIBLE to keep them clean but a wipe with a damp towel can at least keep you tidy
Mine is PRISTINE. Here’s how I do it. I put it in a bag. I go to the show. I look at the thermometer. It’s over 90º and humid. I put on a tech polo and leave my coat in its bag and then it goes safely back in my closet. 
I WISH I could wear my coat more. Doing jumpers makes it easy to leave it in the bag.
Keep a boot brush just for your coat. Brush the dust off and use this.
