From what I've heard and read about a lot of the bigger casinos are regularly using rf scanners to detect any rf signals that are not part of the "normal" casino environment. As soon as you switch on a device like this one on ebay they are going to know it is present and start looking for it. We used equipment sorta like that in fast military aircraft that would fly near or just over the other guy's ship or military base. All of their defensive and offensive electronic equipment would come online to acquire and track our aircraft, plus previously unknown comm channels would get used as they checked with headquarters on what to do. Our equipment would detect these signals and record all of their parameters such as frequency, transmission mode, origin of the signal, etc. That info would all get analyzed, then when we had to do something serious we'd know how to evade, jam, shutdown or blowup their setup. The plane we used at the time was an EA-6B Prowler made by Grumman, it had more electronic equipment on it than you'd believe.