The only horse betting I have done has been the rare occasional tip or with a rare online ponies only bonus.

Many years ago at the Fiesta, they had a promotion where they were doubling payouts on something, I can't even remember what it was called, perhaps twinQ's(?) Anyways, it was huge +EV and could lock up free money betting on all the combinations. It didn't last long, perhaps a week. That's the extent of my horses.

Everyone I ever came across in the casinos who did machine AP and bet the horses were broke and broken.