Am I right when I say that comps are based on average bet times the time played times the type of game? And if so, why do the floor people always want to know what you bought in for and what you left with? The company line is to keep track of the black and purple chips, but isn't there more to it than that?
[Editor's Note: This question is answered by a former dealer, floor supervisor, and casino executive (who wishes to remain anonymous). He or she explains it as follows.]
Actually, it goes like this: how much (average wager) times how long (did you play) times the house edge (how much the casino expects to hold on the game). How much for how long at what house advantage gives the floor a good guesstimate of the theoretical hold.
Now, we always want to know what you bought in for and what you left with, because it’s impossible for floor people to see every buy-in and wager made by every player at every table in their section of the pit, so they're counting on you to tell them (if they didn’t see it) how much cash you exchanged at the table for checks.
There's also a hidden reason for asking a player, "How much did you buy in for?": to tabulate the table float (tray). Doing this can help the floor people determine if a player has rat-holed (sneaked) a few green, black, or purple chips, so as to appear not to be winning as much. Good basic strategy players and card counters like to hide a few checks here and there; it helps dissipate heat from a suspicious floor person. (Heck, Max Rubin actually recommended it in Comp City.)
Tabulating the table float also gives the pit a good idea if the dealer is stealing. For example, a table has been open for 30 minutes, during which time two players have bought in for $50 each, receiving four green chips from the dealer. One player walks with $50 (two green chips). The other walks with nothing. Yet six green chips are missing from the tray. Which way did they go?
Likewise, just before floor people go on break, they take a secret count of the blacks and purples. When they return, they run around checking to make sure none are missing. If any are, that dealer better know where they went and the explanation better be backed up by surveillance or there'll be some grilling and sweating in that dealer's immediate future.
I can’t say as I’ve ever heard of a floor supervisor asking a player how much he/she left with. The pit usually checks with the dealer or calls surveillance for that information.
Many casinos don't allow for extra "discretionary comps" (from a host) for players who win a significant amount (eg $25,000+) during a trip. Also, if a payer loses a large amount, they may receive slightly more generous "bounce back" offers. Contrary to what casinos usually tell players ("It's all based on theoretical"), they DO comp losing players better than winning players, especially suspected advantage players.