One of the best-known cheating sites is Ashley Madison. Curious about what it's like to use such a site, I went undercover (so to speak) for a month on Ashley Madison to take a look inside.
Because I was posing, I was as respectful as possible. I didn't respond to emails or look at everyone's private photos. Obviously, I didn't actually date anyone either.
That said, I was pleasantly surprised by how easy the site was to use.