"Could the Caesars book be showing improvement? Maybe, but I will not be convinced until they stop hassling me to show a room key when I attempt to make a $550 bet there."
What is this guy on another board talking about? Do you have to prove that you're staying at the same hotel where you make a sportsbook bet or something?
I have heard some of the books in Vegas do this, lsu. They sometimes only want to cater to those staying at the hotel - and i.e. lose and spend money on other activities than sports betting.
Even come Super Bowl time, a guy wanting to walk in and put a six-figure bet on a game will sometimes have to be staying at that hotel. To these big operations in Vegas, sports betting is sometimes just considered a 'marketing cost' to bring people in - they just want it to be a side show compared to lots more money they rake in on everything else.