I see these posts all the time of DIY Adwords/FB and then a claim it doesn't work. This would be like me, a non-carpenter, trying to build a house, seeing how bad it looks and then claiming building materials suck. There is reason companies spend ~$70 billion on Adwords annually. So because Adwords/FB didn't work for you doesn't mean their traffic is 90% useless. And dont get me wrong, I completely acknowledge there…
Anyway, if the traffic is 90% useless, doesn't that mean it's 10% useful? I mean, just going by the title. -- Google employee, but not in ads. Take my words with the appropriately sized grain of salt.
But if I then see that traffic behave about 90% like garbage relative than organic visitors -- that puts me at two orders of magnitude off, which is quite insane.