It's hungry for info from ground moving target indicators, infrared video, multispectral imagery, human tipsters, audio intercepts, even text chats and social media, among others.
And while these scandals are scary enough, the retaliation that tipsters and/or whistleblowers often experience is inexcusable, but unfortunately real.
Good tipsters use statistical based estimations and extensive research about the outcome of a game, and compare this estimation with the bookmaker's odds.