from the book Smart Money
“Thanks to the general brilliance and accuracy of the point spreads, gamblers who can consistently beat Joe Bookmaker are as rare as honest politicians.
But it can be done.
The bookies fear (and despise) a tiny coterie of professional bettors known as “wiseguys,” or “the sharps.” Fewer than 0.0001 percent of gamblers, the proverbial “one in a million,” are able to consistently pick point-spread winners. But there are betting syndicates privy to the most up-to-date information on injuries, weather, game plans, and, most important, the real power of the teams involved. These wiseguys are often able to derive a more precise, more accurate, more valuable point-spread line than the oddsmakers. Essentially, they create their own theoretical line on the same slate of games offered by the bookmakers. Then they compare their numbers against the bookies’. When the sharp players spot a discrepancy between their line and the one the bookies are offering, they bet.
A lot.”