I am not an expert here, but have not really heard of the humidity thing with Guitars. I imagine that in extremely humid environments, there could be issues, but I would not put beads in with your guitar. Most guitars have a metal bar embedded through middle of the neck to prevent warping and what not. Temperature on the other hand can play in. Keep guitars away from the cold particularly. I know there are other players on the forum so I am looking forward to seeing more informed responses to this thread trickling in.