My guess is that hosts might share information on their mid/lower roller clients between eachother..purely anecdotal though:

Last time I gambled at a harrahs property, it was 2005 at the Rio and I was probably $25/hand blackjack player...

Fast forward to 2010, got assigned a host at the MGM Grand (already had hosts at several other MGM properties) .. rating on the trip was $325/hand craps..

Get back home..have a voicemail from my new host at caesars palace..haven't *ever* gambled at caesars, and last gambling at a harrahs property was 2005 @ the rio..


..Just seemed like way too much of a coincidence to me.