A fictional signup bonus offer:

The online casino slot machines offer new players a deposit matching bonus of 100%, up to $100 The player must wager 25 times the total amount of the deposit plus the bonus before withdrawing Wagers on baccarat, craps, roulette, and sic bo do not count towards meeting wagering requirements For this particular example, this would mean that a player depositing $100 would start with $200 in his account. The player must make $5000 ($200 × 25) in wagers on online casino slot machines before being allowed to make a withdrawal.

Advantage play in casino signup bonus situations is mathematically possible. For example, the house edge in blackjack is roughly 0.5%. In the example above, $5000 in wagering with a house edge of 0.5% will result in an expected loss of $25. Since the player received a $100 signup bonus, the player has an expected profit of $75.

Advantage players who use bonus offers for an expected profit on online casino slot machines are often called "bonus hunters", "bonus abusers", "bonus baggers", "bonus whores" and "casino scalpers". Some online casino slot machines have restrictions regarding "the spirit of the bonus offer" which they sometimes use as a deterrent to what they consider "bonus abuse".

A player who wishes to do this at a large number of online casino slot machines must be careful. Some casinos are rogues (see below) and do not pay. Others have terms and conditions that are not favorable to the player, such as most bonuses that are restricted to slots.

So, should you play online casino slots? An Economist explains...
While getting my MBA one of the concepts that I actually found pretty interesting was the utility curve theory of money. The way it works, basically, is to look at the marginal utility of each additional dollar you have, rather than its fundamental economic value.

For instance, to a starving fellow in the street with no ready money at all, the marginal utility of a single dollar is incredibly high, as it can mean at least a bit of food that might literally wind up saving his life.

However, for me (luckily), my quality of life is so completely unchanged whether I have an additional dollar or not that its utility is extremely close to zero. I would likely never notice if a dollar happened to fall out of my wallet once a week for the rest of my life.

However, on the flip side, for me (unluckily, as I've not wealth of that magnitude), my quality of life would undergo pretty drastic changes were I to win the lottery.

So, while the utility lost to me from spending a dollar on a lottery ticket is extremely close to zero, the utility gained were I to win would be astoundingly large.

Therefore, it likely makes sense for me to subscribe to the lottery and have it auto-deduct and play a ticket for me on a weekly or bi-weekly basis. The subscription/no-work-involved aspect is key, because if you add in the utility cost of actually physically going to buy a ticket you lose immediately. It must be as nearly zero-effort as possible in order to maintain the utility/quality-of-life positive balance.

Ideally, if I could literally forget it was even being played for me, aside from a $52 deduction per year out of my account, things would be nearly perfect. I'd never miss the $52 as far as my quality of life goes, and yet I'd always be poised for some pleasant surprise that would make my month/year.