There are few human instincts that are less powerful than winning. With that, however, comes the unfortunate problem of cheating. In the real world, cheating usually has a fairly direct consequence that makes you not want to do it again. Out in the online world, however, things are just a bit different.

Consider, for example, eBay. The number-one online auction site recently started a promotion called Holliday Doorbusters where people could buy certain items, from sports cars to mini-saunas for the low, low price of one dollar. Sounds like a good idea, right? Unfortunately, things didn’t work quite as planned.

The promotion’s catch was that the first user to find and bid on certain items wins. However, it didn’t take long before clever coders created scripts that could find and buy the steeply discounted items before humans could. It reached the point where some items were bought before anyone actually saw the items.

eBay’s response was not exactly confidence-inspiring. It isn’t clear whether automation tools like scripts would constitute “fraud”, and whether buyers using such tools would have their bids voided.

While this may be the most recent case of this kind of online fraud, it wasn’t the first. Earlier, a contest to decide which school would be the first to be featured in a Victoria’s Secret line of lingerie turned to farce when enterprising users learned how easy it was to flood the voting system with votes for their preferred school. Victoria’s Secret was eventually forced to restart the competition.

Real money has also been lost over cheating online. The online poker room Absolute Poker was hit last year by a scandal that revealed it was possible for gamblers to see the cards of everyone else at the table. Estimated winnings are reported in the half-million dollar range.

Online opportunities have only grown, however – and together with that, the incentive to cheat. So far, none of these instances have been truly calamitous. However, each one – and others like them that have not received attention – just highlights the fact that many online systems are not built with good security in mind.