...have the habit of wiping their hands under the seat after eating a piece of cake or sweets.
I just did.
It's normal practice that folk bring sweets when they are back from their hometown and cut cakes for somebody's birthday. A colleague just walked upto me and offered a piece of black forest cake, I took it with the help of my thumb and fore finger and tossed it into my mouth and relished it.
Now my hands were soiled, soiled as in not completely, but still you have that feeling in your fingers, automatically my hands went under my seat and voila...simple and easy. While I could have got up and walked up to the restroom at the other end of the floor.
Many a times people do it subconsciously, they don't even realise it. Today I did and will try to consciously remember not to do it again :)