What is the best way to catch a cheater?

I personally am in favor of using a keystroke logger which is a computer program that records every single keystroke that is made on that computer. The results can be a little difficult to interpret but are very much worth as it is almost impossible to hide anything from it. Keep in mind that it probably is illegal to use such a thing on any computer that doesn't belong to you. I have used these programs on my own machines and have caught women cheating on me as a result when they have used the machines. The programs are cheap and easy to install and send results to your own email only if you wish.
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I forgot to mention that it is also almost completely impossible to detect or remove one of these programs unless you have the locking phrase which is provided at the time you purchase the program. Again, totally worth the money and the peace of mind that you get from knowing the truth.
What is the best way to catch a cheater?
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