FHSS is not magic. In some ways it makes things worse for other protocols while avoiding problems for itself.

Which leads me into The next comments you made about interference sources. With microwaves and LED bulbs and such. While I do have an SDR, I don't use it for wireless cleanliness. My access points, mainly Cisco aironet 2802i series, have a feature called "clean air" which isn't new for Cisco, but other vendors are starting to add similar features to their access points. I believe it's been included in most mid-range aironet access points since wireless N (around the 2600, maybe before)... Anyways, the built in radios will listen for and analyse interference and provide information related to it.

Clean Air will report pretty much everything that can be interference with decent accuracy. I've personally seen the following: radar, Bluetooth, microwave (oven), and "non-wifi" as interference sources. I believe "non-wifi" is the catch-all for something that can't be identified.

Clean Air also reports on what channels are impacted by the inference, and I can also get reports on nearby wifi networks, and what channels they're on, the frequency width that's set on foreign access points.... On top of that, it gives me a report on how busy the channels are for the configured channels on the access points, with classifications for my wifi traffic, others wifi traffic, noise, and inference.

With microwaves, I mainly watch the clean air report, if I see microwave (oven) interference, I try to reference the time of the interference, and figure out if the microwave was in use during that time. If it lines up consistently, time to replace the microwave.

In my experience, new microwaves rarely have an isolation problem. The mark quality in the manufacturing of the microwave, is how long before that happens. Some last a long time, others lose their isolation fairly quickly. Pre-testing isn't very useful since the isolation is usually fine when It's new.

To the same point it'll pick up interference from other sources, like lightbulbs. So if that's picked up at all, I'll have to correlate what lights are on and when, to figure out which ones are the problem. To date, the interference is either off-band, or not significant enough to trigger clean air.

I know CFL's put off way more RF interference than LED bulbs. The high frequency required for florescent lamps is far worse than the RF put out by most LED bulbs.

I've considered getting an ekahau sidekick to get a better wireless spectrum analysis, but there's no way I could afford one right now. If I had more of a purpose for it, beyond my curiosity, then maybe. As it stands, no way. It's in the neighborhood of $2000+. Unless I can use it to help pay the rent, I won't be picking that up.