While that saying might be a tad unjustified, I find that their products are often purchased by people who don't do adequate research into other headphones that might suit them better. I often see people wearing the "QuietComfort" brand headphones in situations where they gain no benefit from active noise cancelling, although for all I know they could be heavy travelers and only own a single pair of headphones. But honestly, a comparable pair from another brand would run them $200 less...
The only time you really want the active stuff is when you're traveling and there exists a lot of low-frequency noise, such as on a train or airplane. Looking around on Hydrogenaudio confirms that the QC are okay if that's all you need, and also that alternatives exist, such as IEMs, which might have a wider range of use as they simply have very heavy passive isolation.
The e5c's main problem is they are SO sensitive they are completely unforgiving about the amplifier used - almost anything with a gain block after a volume control is going to have too high an intrinsic noise floor for them to not show it up.
Here's what the wirecutter says about it: http://thewirecutter.com/reviews/best-noise-canceling-headph...
At home I also have the Sennheiser HD 600. I usually use the Bose -- the noise cancelling is nice even if you're not in a plane.
I'd be upset if my home environment were loud enough to warrant noise canceling, though.
In terms of pure isolation, Etymotic makes some of the best out there (>30dB isolation), and I think they sound absolutely brilliant.
Bought some QC15s at 2 am in the Atlanta airport on a cross-country-twice-in-48-hours trip. Probably the best $300 ever spent. Slept like the dead. No one bothers you with those headphones, and they aren't nearly as heavy as a lot of fancier stuff, or as insulated, so your ears don't sweat.
Those are my go-to ears at all times. I even got a carabiner so I can clip them to my bag (also a superb product: http://www.saddlebackleather.com/Classic-Briefcase-Thin)
