Hmm. Okay, here's a purely hypothetical situation. Just for the heck of it. Any resemblance to living persons is purely coincidental.
So let's assume one's at, say 1 Utama. And you go to the washroom to take a leak. As you go in, you see a highschool lecturer of yours from St. Paul's, who had just done his business at the urinal and was walking out. There's immediate recognition, and so he extends his hand out to shake yours.
Except you had seen that he was just done at the urinal, and he hadn't washed his hands!
So, question is, should one return the gesture and shake his hand?
I read somewhere that up to two thirds of men don't wash up.