Since "most" of lv is now owned by either mgm group or harrahs, it is interesting to compare their comp systems.
With harrahs, as you play slots (with your total rewards card in the machine) you accumulate base and rewards points; the latter can be used as cash toward eating in resturants (or even paying your hotel bill)--this is yours to use as you want.
mgm system is a "secret" comp system. If you want to get comped for a buffet, say, you go to the players club desk, they look at a computer screen (which you don't see) and based on your play can acceed to your request (or deny it.) In some sense, under this system, you feel like you are "begging" for a hand-out. On some occassions this system can work in your favor--but you really don't know what the rules are.

Harrah's also has secret comps for decent players after you exhaust your rewards credits. And MGM has non-secret cashback for slot players while Harrah's sends you secret cash later.

QL

YES...last time I checked out of Caesars Palace after a disastrous stay, all of my (substantial) charges were comped even though I did not have the rewards credits to cover everything.

In my experience, you are in a better position returning to an MGM/Mirage property after a winning trip with high action than you are to a HET property in a similar circumstance. My best upfront comps have been to Mirage and Bellagio after WINNING trips.

OT, if you have a truly horrendous ($25K+) loss, some houses (Mirage and TI for sure) will comp absolutely everything including the "uncompable" tips, massages, gift shop, and phone charges...