Re: Noise problems in general
This post suddenly reminded me of two incidents I dealt with over the last ten years, in my real job. I'm a software guy, so how I get roped into these issues is beyond me but there you go!
1. I had numerous network issues in a shop over several months. Eventually I decided to do a site visit and prove to the engineers that the software was fine. I had a good look around and noticed that one of the CAT5e cables was routed over the suspended ceiling and it was pulled tight so that it went over the top of some fluorescent strip lighting. I speculated that the network comms was being disrupted by the lights. When they re-cabled the shop, the problem went away.
2. I had another store that was reporting numerous issues with their PED's (Pin Entry Device - you put your debit card in them at the Point of Sale to pay for things). Again it went on for months and I kept getting dragged into it because I supported the software. Eventually I went on Google Earth and found the site. There were high voltage power lines running right over the top of the building. I recommended that the site switch to a different model of PED and the problem went away. That may be the first and last time that Google Earth has fixed a retail 'software' issue for me. 
Both of these examples are nothing to do with AES50, X32, Behringer, S16 or sound engineers. Yet both clearly illustrate that CAT5e is susceptible to outside interference.
Thought you might find that interesting. Now I'm going back to page 276 to continue my catch up!
