I worked at this observatory in the 90's to help enforce the quiet zone. The people in the area were highly educated, not typical hillbillies. I met a few nobel prize winners and had the opportunity to meet Grote Reber who was there one summer delivering his memoirs to the observatory.
Green Bank has easy access to a ski resert, whitewater rafting, caving, rockclimbing, and mountain biking. That part of W Va is quite an outdoor sports mecca. The location and the people should not be dissed at all, since they are exceptional compared to the average Slashdotter!
The quiet zone is a regulatory creation, and I know local folks in the area sometimes had non-compliant transmitters. For those obsessed with EM, note that just because there's a regulatory quiet zone, it doesn't mean that people aren't still using Wi-Fi. They just haven't been busted yet!
It was usually only an issue if an astronomer complained about interference swamping out their observations. The interfering frequency would have to be in the RF passband of the observation. If the signal source was in the band, it still has to be in the beam of the antenna or couple into the system via cabling, etc. to be a problem.
There is a schedule that shows which receiver is installed for the observations being done today:
If interference was seen, we tried to identify the modulation on a spectrum analyzer to decide if it was a faraway source such as a TV transmitter, satellite, or aircraft. We had a communications receiver where we could snoop conversations to identify the nature of the broadcast. If we suspected a local source, we would drive around town in a truck fitted with a spectrum analyzer and a directional antenna. When we found the source, we would help the individual or organization come to compliance. Interference could be nonintentional, such as power lines or even a farmer's tractor. :)
I have fond memories of the observatory, I got to experience Ethernet when it was coax and TCP/IP before the Web existed! (Gopher, Archie, telnet BBSes and such). One former employee ran a MUD at the observatory that wasn't discovered for years. If that's not Slashdot-worthy, I don't know what is! :)