Spent some time ages ago at Yonkers and Rooselvelt Raceways (trotters) with my former brother-in-law, who lived there for awhile. He knew all the big and mid time regulars there. Quite a few would show up loaded with cash and a system for a period of time before disappearing after they ran broke.. then after putting together another roll they'd return and try again.
One system that a pair of players had some success with was very interesting to watch. A few minutes before the the bell the two of them would wind up being the last ones at the $100 windows. Don't know how familiar everyone is with the way they start the trotters, but essentially they have a car with an extended starting gate that the horses run behind and just before the starting line the car takes off, withdraws the extensions and the horses take off a short distance before they actually reach the starting line. Well, these guys would stand at the $100 watch as the car pulled away and yell the number of the front running horse to the cooperating parimutual clerks who would punch out as many $100 tickets that they were able to until the horses crosses the starting line (about 5-10 seconds) and the machines would automatically shut down. I guess the clerks were able to punch out a bunch of tickets, for a nice tip, of course.
These guys did pretty well with this system for quite a while, but, alas, after a few weeks they too disappeared. The front runners win sometimes, but definitely not always. Came back a few more times, busted and disappeared again.
Lesson I learned long time ago: Systems do not work forever. Most gamblers don't even care about winning or losing, they just need the action.
Jim