One way to beat casinos is to play at any of the many No Deposit casinos. If you do not have to ever make a deposit in a casino or an online bingo casino, the ability to win is enhanced and the worst case is that the free money in used up and the player must just go to another No Deposit casino. There are so many of these online now days, it would take a while to make it through the entire list of casinos. A long the way there will be obstacles like not being able to take out any winnings until a deposit is made. There are also play through rules that must be lived with and there is no standard rule about these rules. It depends on the casino and there is not any logical reason for one set of rules vs another set on a different casino.
Casinos are an entity to themselves and they can set whatever rules they want for their casino. There is no higher authority for these online businesses in this area of casino management.

If the casino has reasonable rules and you win with the free money, there is the possibility that you will be able to take out some money by playing through the betting requirements.
I did this on one no deposit casino by meeting all of the requirements and still having over $400 in winnings. This casino did not have a limit on winnings. The game played to do this was 3 Card Poker. This game is a winner since it has wagers that can return 30 or 40 to one on your wager. At one time I had the winnings up to over $2800. Of course at that time I did not meet the play trough rules.

Online bingo casinos are another area that gives out free money to try the site. If a win is scored on a big jackpot, most of these casinos have a rule about how much you can win with the free money. Most also have severe play through requirements and deposit rules on money won with free money. If you are going to do this make sure you understand the rules about winnings from free money. If there is no limit, then have at it until the play through is covered and then bail from the site. Expect some other ID requirements before you finally receive you winnings. These requirements usually entail sending fax copy of a drivers license and the face of a credit card you are using to make deposits. The claim is they want to make sure that you are who you say you are. But notice there is no ID rules when sending money to them.