I found this part very interesting..........................
The system is hardly a fair one for the majority of a track's customers. The gamblers getting rebates have a huge competitive advantage over the long-suffering souls in the grandstand betting at a 20 percent takeout rate. Peter Berube, general manager of Tampa Bay Downs, examined last season's wagers from rebate-shop customers and saw that these sophisticated players -- presumably the computer groups -- were winning at an astonishing rate relative to everybody else. "They're fleecing the rest of our customers," Berube said, "and this season we decided not to allow them access to our pools." Tampa Bay became one of the few tracks to cut off the rebate shops.
Gamblers who look at Tampa Bay's takeout rates -- 22.5 percent on exactas, 25.9 percent on trifectas -- might reasonably say that the track is equally guilty of fleecing its customers. Few horseplayers have a chance to make a profit betting against the sky-high rates that prevail at most American tracks.