You'd think that running a competition would be a fairly painless marketing strategy, however there are issues that you should be aware exist.
Unfortunately people do cheat. Whether it's using shared answers or finding ways to circumvent your trivia quiz or using programs to get high scores on prize games, if they can do it, they'll do it!
There are people who like to enter competitions! It's their hobby and they frequent site's like Loquax. On one hand most can be good for your competition on another some can be a problem. We actively encourage our users to stop and think about their comping, but some will still enter anything and everything online. They perhaps just like the thrill of winning or want to win stuff to sell.
3. Automated Entry Services
If you're running a competition and you want people to visit your site, then you need to be aware that automated competition services exist. Basically people pay subscriptions for a bot to enter competitions on their behalf. In short you could be giving out your prizes to someone who's never seen your site.
4. Sharing Answers
People like to help each other win stuff, and that means answers may well be shared on forums and websites. This might mean people don't click through to your sponsor to find an answer or visit a certain area of your website. It can also mean that your cleverly crafted quiz or treasure hunt in essence becomes a free prize draw as the "competition" element is lost.
5. Posting Your Competition Email
If you post your email address on your competition page then sometimes it will be posted, along with all your competition details, to a forum or newsgroup. This means you might get loads of entries, but they'll be from people who haven't visited your website. They're also a favourite of autoentry services and spammers!
The good news though is that there are ways and means to combat each of these issues!