Stuxnet for example, didn't really seem to do anything useful. Unless you happened to have a very specific version of industrial control software installed. No

Stuxnet for example, didn't really seem to do anything useful. Unless you happened to have a very specific version of industrial control software installed. No obvious payload is actually the worst kind of malware to deal with, because you have no idea if Matthew in accounting had the specific key on his machine that installed a second stage that you know nothing about and can't detect.