Actually, I know for sure that alcohol is hygroscopic. And that's why I only open the cans when I pour some out, and put the lid back on. And when I plan to leave jugs open for a year or so, I expect there to be some water in whatever was in the jug.

One of the real problems our hobby has is that lots of people hear a true statement like "alcohol is hygroscopic" and next thing you hear is that it'll suck the humidity off the walls in the house next door. It's really hard to keep a perspective, but that's what's needed.