I'd imagine the Napster criteria of "substantial non-infringing use" would be used to differentiate between Dropbox and Megaupload, so I doubt either the company or its employees would have a problem on that front.

But there are lots of companies that break the law so blatantly that their employees cannot claim to be ignorant. For instance, if I were an employee of Uber, I would be very careful traveling and would take every opportunity to hide the identity of my employer, especially if I were going some place where Uber was particularly irreverent of the local laws when trying to enter the market.