I believe I once ratholed "accidentally."
During my recent trip to Vegas, I never deliberately ratholed. I moved from casino to casino (Aria and Bellagio mostly), trading my chips over at the cage.
And yet, for some reason, at the end of my trip they had massively overestimated my actual loss. I actually made 1200 in winnings but they apparently believed I lost about 3000 or more.
This was probably due to a mistake made when I was being rated, because I kept all my chips in clear view.
And yes, Stupid Honest Me actually did inform the casino host of the mistake. I still am not sure if it was the right thing to do; it was clearly the mistake of the casino rather than anything that happened on my account. Especially since every time I exchanged my Bellagio chips for Aria chips and vice-versa, the casinos talked to each other on the phone to verify things. So the mistake was clearly not my fault.
On the other hand, I prefer conducting myself in an honest manner, especially since the comp system at the MGM properties is pretty generous. I get back 40% of actual or theoretical losses, whichever is greater. Additionally, the house assumes a theoretical loss at BJ of 0.7%, so I get back 40% of 0.7% of everything I bet in comps.
I ran some numbers based on my actual play stats from my trip to Vegas (4 hrs a day, 9 days, average bet $42, casino assumes 70 hands per hour) and I was comped $300. I crunched the numbers and got the assumed house edge of 0.7%.
Then I looked at the "effective house edge" on a bet of $100; casino assumes a loss of 70 cents per 100 dollars bet, and the player gets 40% of that back in comps. This means the player gets 28 cents back, so the casino assumes the player will lose (70-28) = 42 cents a hand.
However, a basic strategy BJ player, on a liberal Strip rules game (which was the game I played) will lose 28.5c (on average) on a single $100 bet on the blackjack tables.
In other words, on a flat $100 bet per hand, assuming a 40%-theoretical-loss-comp, a casino will make 0.5 cents per hand off a rated player that plays perfect basic strategy at a liberal vegas strip rules game.
Then factor in two considerations;
1) Free drinks at tables
2) I deliberately play slow, so there is no way in hell I was playing 70 hands per hour.
I don't even card count, and assuming my mathematics isn't completely wrong (I admit this is an extremely shaky assumption because I suck at math, so if anyone sees any errors please inform me), then the casino already makes basically nothing off of my play (and indeed, off any perfect basic strategy player).
So then I ask myself, do I even need to rathole?
(note: the above is based only on theoretical losses; the MGM players club comps you 40% of theoretical OR actual loss, whichever is larger. This only makes it more generous).