Landing gear micro switchs

Preflighting the Arrow I was taught to check the landing gear micro
switches. OK great. There they are. I even work the switch to feel that
it's making contact inside. I was Master Mechanic in the Air Force and
repaired the Autopilot systems on the SR-71 and U-2 so I know about
airplane systems and parts and all, but what exactly am I supposed to be
checking? That they aren't caked in mud? That they are there? I can't see
if the lights are working while I manipulate the switch so what's the deal?
None of the CFIs can give me an answer besides, "check the landing gear
switches". I'll keep "checking the switches" on every pre-flight but can
someone provide a more detailed explanation on what I should be checking
for?

Thanks.

Lsoup