Do not spray WD40 on any electronics, use electronics cleaner. (Hexane, it evaporates completely). WD40 leaves a residue that can prevent good contact.
When you spray WD at the clutch switch it really only deals with the plunger and the dirt and grit. It helps to loosen up the grit and lubricate the plunger. Electronic cleaner won't help loosen things up. I would agree if you're tearing it down and cleaning. Or if you were going to spray it down afterwards.