Mine smell like dirty socks. Makes sense really as hands and feet could sweat the same way? Anyway, one of the amazing things I discovered when I learned to ride was that one needs to think of gloves in the same way as socks, and wash them quite often. Hence we have quite a lot of those cheap cotton bobble ones - and two Roekls too these days. I may wash three pairs at once in the bathroom and hang them straight over the bath to dry.
It is a bit shaming how much brown dirt comes out. So I may leave them to soak for 10 minutes or so.
If I were a professional like you and your daughter, riding several horses a day, and had socks to go in a machine wool wash cycle, I guess I might try putting an old pair of gloves in with the load to see how they do. But my gloves are so disgustingly dirty and the Roekl ones so precious, that I have never done that.
There is a big difference between professionals like yourselves for whom riding clothes are work clothes and people like me for whom riding is a luxury and who cherish anything that has cost more than the minimum. What happens to my older Roekl gloves is that the outside coating peels off. But the cotton ones shrink and go into holes. Cost per wear probably not much different?