Do casinos really use expected value calculations? I wonder if casinos really care about the expected value of certain games.
Suppose my game has a negative expected value (so the casino wins) of \$5.
Now we have one player playing the game. Would this not mean, that no matter how often the player plays, we could get a maximum of \$5 out of him.
But \$5 per player does not sound a lot to me. To me this would imply, if I had only 10 players visiting my casino I could only profit $50 and that only if they play for a long time.
Would it not be more reasonable to have something of an "adjustable" expected value that goes to minus infinity, so that if one person plays the game often we could expect a bigger profit than if he plays it only a couple of times?
 A: By the definition you have ascribed to the phrase "expected value", I doubt that the casinos give it consideration.
However, usual meaning of the term "expected value" is very different from how you are using it. The usual meaning of "expected value" is already what you call "adjustible" — the expected value of playing $N$ times is $N$ times the expected value of playing once.*
(to be clear, I mean that if you go to the roulette wheel, stay for 27 spins, then leave, you have played the game 27 times, not once)
*: I assume for simplicity here that you play the same way each time. If you vary your betting, you need to make the appropriate weighted sum, but works out to the houses expected take to be a fixed percentage of the total amount you bet over all plays. Similar adjustments need to be made if you place bets with different odds — e.g. in roulette the house expects a greater percentage of your money placed on five number bets than it does on other bets.
A: The answer is no. 
Any such system would make the game heavily in the favor of the casino when a player plays first time. But then, why would any new player play the game? If a Casino cannot attract new players, they would become broke after a while...
A: In the casino example, the expected value is what your average gain/loss will be when you play the game "for a very long time" (let the number of plays $\rightarrow \infty$). You can think of this like a horizontal asymptote. Functions can cross horizontal asymptotes infinitely many times (just look at the function $\sin(x) / x$), but as you let $ x \rightarrow \infty$ the function gets closer to the asymptote. Assuming certain betting strategies your gains and losses will fluctuate greatly from each individual game, but if you play the game enough times you'll get closer to the expected value. In practice, if someone is on a cold streak and is losing money they will be discouraged to continue playing so their number of plays will terminate before approaching the expected value.
As mentioned in the comments, however, you need a nice balance because if the expected value is too large in the casino's favor, people will always lose and no one will go to your casino causing you to go out of business.
So I don't know for sure, but I'd say it's possible that for certain games some sort of expected value is utilized.
A: The expectations are tuned in such a way that they are minimally positive for the casino, because otherwise another bank, or casino, disguised as a player would be able win again the first in the long run. Nevertheless the rules are looking pretty fair and "interesting" to the prospective player.
This minimal edge for the casino is guaranteed, e.g.,  by the two zeros. For  the average player they don't have a big influence, since usually he is broke due to limited resources before their effect plays a rôle.
The decisive reason why the casinos have the upper hand is the fact that usually players don't stop before they have lost all their money.
