Since there seems to be disagreement among the troops I thought I'd put in my 2 cents. WD40 will certainly work on low voltage/current switch contacts and Pots in the short run but in the long term it's very, very bad. WD40 contains silcone. Over time, especially if not used, a pot could freeze to the point of breaking it before it will turn. I've also experienced it morph into a tacky goo! From a field expedience point of view, I would certainly use it in an emergency though.
As a side note and just to give some perspective of what WD40 morphs into over time.. I have a wood/machine shop. One of my lathes is a 1952 Logan 920. When Hurricane Wilma blew through here my shop had roof leaks popping up every where. While running around in a panic, with no lighting from power outages, I sprayed her down with WD40. After that, life and work got in the way, so she sat for over 5 years unused. There is no rust on her but the tailstock is absolutely fused to the ways. I'll be using some Krell on her or whatever to free it but that's not the point. Over time WD40 will turn into a hard varnish.