Engineers *usually* wish they had never met sales people, but not because of their clammy hands. A sales person generally stays well clear of engineers unless they have outrageously oversold something and need someone to rewrite the laws of physics.
It never pays to shake the hand of someone in sales... I've noticed that Dilbert has found joy in causing pain to his coworkers in every way possible. He's not going to let go of that hand until the guy is in tears and planning to jump off the building.