traffic quailty on adwords vs facebook ppc

Quality has less to do with the network than how you do things. There is also the type of network. Google is a search engine so you can grab someone's attention with an appropriate offer based on the keywords they searched on. It also has a vast content network but so does Facebook. Typically, search is better quality but it can depend on who you are targeting.

It was many months ago, may be close to a year now and I think here on WF. A guy was selling a book on football statistics I believe. If you use Google and other search engines to show ads whenever someone searches for football statistics, that should be better quality than simply targeting those interested in football. Provided a good ad, you could get a lot of clicks for those searching and provided a good sales page, convert a large portion of them. On the other hand, targeting football fans, not everyone of them are into statistics. You may get a lot of curious clicks so your conversion rate is lower. Your ads should be different than for those searching. You may want a different landing page too to cater to each type of visitor.

So it's not that A is better quality than B. It's how you use the tools. Take advantage of each of their strengths.