If it's very hot and Scout's really sweaty, he'll get a hosing and the excess water scraped away. Otherwise he gets a quick brushing to get the sweat off.
I've read that an in-depth grooming is most beneficial post-workout, because the pores are open and sweat has helped to being that skin-deep layer of nasty closer to the surface to be brushed away. For the same reason, mane pulling tends to go easier after a ride.
Also read that foamy sweat is a result of dirty pores, and a horse who hasn't sweated much recently. More frequent sweating, less crud in the pores to make foam. Whether that's true or not, I don't know, but I thought it was interesting.