Computers were once big RF emitters, but the FCC cracked down on that successfully in the 1980s. In the early days of personal computing, a Radio Shack TRS-80 and a Milton Bradley Big Trak would both crash if close. In recent years, most computers got radio receivers for at least WiFi, and thus had to be built well enough not to knock out their own receivers.
Analog TV sets tended to emit loudly at the local oscillator frequency. The UK used to drive around with "television detector" vans to find people who didn't pay their TV tax, which funds the BBC. But tuners quieted down years ago, as they became tiny RF-tight sealed units.
The worst behavior comes from switching power supplies, especially for lighting. The cost pressure is very high. They don't receive, so they have no receiver to protect. Another big source of noise is leaky cable TV systems. Again, since they don't receive, they aren't affected by their own leakage. The cable industry has successfully lobbied to escape tight restrictions on cable system leakage. Those two sources are probably the source of most problems.
Low-cost spectrum analyzers are available, and some are laptop peripherals.[1] There are ones as cheap as $69 on eBay, but the consensus in EDN is that you have to pay a few hundred dollars to get something that produces useful measurements. People who install and maintain WiFi networks in large buildings usually have one. Then you can find what's blithering all over the spectrum.
[1] http://www.edn.com/design/test-and-measurement/4412405/Low-c...