Of course, it is possible to make an anti-cheat system if you have the cheats, but usually, it doesn't work with cheats that work as plugins because they are hard to detect. You can find such kinds of hacks on
iwantcheats.net. I bought some hacks for Call of Duty, and the first period I thought that I would get banned soon, after the first game with hacks, but I was wrong. I still have my COD account, and it is not banned. I have played a lot of hours with hacks, and I wasn't banned because the anti-cheat system can't detect the hacks I am using.