If someone is looking at all your private devices, etc...at work it's someone like me lol. Arp table on your pc collects the macs of everything in that LAN. Now, I don't care about that but seeing my own devices log that and my IP and evey USB drive and knowing how many people, devices and companies have/process that information is what led me to those precautions. It's also standard practice to look at all the SSIDs you've connected to or sometimes USB pid/vid inserted before file writes when doing foresnsic investigations (usuallu happens when you're suspected of being naughty or simply because of a special/sensitive role you hold)

When it comes to personal devices, USBs are the ones I have to track down a lot because of worms and all mostly. But I have ran into people that mount smb shares or whatever to a device in their personal lan that has all sorts of malware infested pirated shit (I just get them to stop connecting it).

Also, urmmm... how can I put it? There are some really terrible people out there including people that may or may not work at your company's IT/sec/mgmt.

YMMV -- I know what I've seen :(