Hand Washing Station

I did some bike work last weekend, but I don't have any of that special soap that takes bike grease off your hands, so I had to stand over the sink using Dawn for ages. In the course of washing my hands, I realized that I'm terrible at washing my hands. I'd get most of them clean, but my thumbs would still be black from grease. Is this a personal issue, or are we all walking around with disgusting thumbs and no knowing it?