Per Valleywag anyway.
I can definitely see why they’re considered the worst. Actually, I’ve seen offices that have been in worse shape, but had a lot of personality and warmth. Most of these just look cold and impersonal. Not exactly a welcoming employee environment, even if your company has “headphone culture”, that is, a line of employees coding all day long with headphones on.
They also had the 10 best and they are really that good.