Tips To Stop The Cheats
1. Don't publish an email route to enter the competition. Use a web based form system and collect IP addresses as part of the entry process!
2. If you are running a quiz/game/treasure hunt, don't allow people to access your entry form until they have genuinely completed the competition.
3. Regularly change your questions. Use a script to randomise your question!
4. Monitor your web traffic and referrals.
5. Keep an eye on entries - including email and IP addresses. Set cookies or use SQL database restrictions to help reduce multiple entries.
6. Keep an eye out for Automated Entries.
Remember it is your competition and should be entered as you have devised it for your website. Allowing cheats to prosper negates the reasons for running your competition.
Online Games
Cheating mainly tends to occur through online games, normally java or shockwave based. Some people have learnt (or already knew) how to break in to the games and register high scores.
The images below are from a lastminute competition that ran some years ago, but it demonstrates that cheating can and does occur. In this case, lastminute acted swiftly to make sure their competition was played fair and square and all persons found to be cheating were disqualified from the competition.
Allowing everyone to play on a level playing field should be the aim of everyone who is running a competition, especially interactive games that need high scores to win.
Stopping the cheats should also be paramount in administering a competition. If you have a game competition look for abnormally high scores (You did try the game out first didn't you? Checked for bugs? Tested others with the game? Have a vague idea what is humanly possible and what isn't?) and listen to complaints (and take them seriously) from other users.
If you find that someone is cheating then disqualify them! If people feel that they can't participate fairly in a competition then they'll stop participating.