The worst part about OCD is that your brain is at war with itself. Unlike some mental illnesses, you are fully aware that your mind is tricking you. With OCD your brain is a double agent that keeps feeding you false information, but just enough true information that you can't trust it. It's not that everything is distorted; it's that what is and isn't distorted depends on the flip of a coin (and you can't even trust the coin).
My senses contradict each other. My eyes can see that my hands are clean, but my hands feel stuff on them. And sometimes the opposite is true. I hate this so much.