I think the reason why there as so many for sale on ebay is due to good marketing by Brodex/Ionics/Freedom etc.
Lots of people who have been made redundant and have a pocket full of money looking for a job are sold the hype of earnings thousands by cleaning windows using wfp.
They buy into it, spend a big wad of their redundancy and then realise that 20 years sat on their arse in a office is not good preparation for the realities of window cleaning, grafting all day in all weathers! 
So they jump ship and sell up their "nearly new" WFP window cleaning systems.
It's not that the systems don't work, it's the operator that doesn't work......in my opinion 
Ian is right, its all about the people. Can't hack it. They would last even less time on ladders. However, please carry on knocking WFP, the more people you can put off it the better. Too many converting round here, thats the last thing I want to see.
The more dippys on ladders the better for me, they can't to the one above the conservatory, they cant do the one above the garage, they don't do the frames, they don't do the front door.
I always have to laugh when I hear people on here saying they pick up loads of work from WFP window cleaners. Really? because my experience is you lose customers to WFP .