Well not so much the public.
Lets say that Billy Walters puts out a FALSE order to a few of the movers on his own payroll. Now they go and play some side for 100K, now that shop moves the number, and other shops follow on "air" as they do. He could have other movers waiting in that 2-3 mintues to buy up the other side at that moment. He is famous for that kind of thing ! Now he has one side at -something and the other side at + something usually a full point, 2 ways to catch a tie and win the other side. BW and other major groups set traps for others almost everyday.