"how many folks who donned a Guy Fawkes mask were really affiliated with Anonymous?"
Every. Single. Fucking. One.
The social dynamics of Anonymous are really not all that hard to understand. Everyone who chooses to self-identify as Anonymous is Anonymous. There are within Anonymous hackers and non-hackers. Amongst the hackers there are numerous hacking clans; but are are separate and distinct as well as being Anons.
Really, it's not that hard to understand. Think of being an Anon like an internet nationality. You can be from New York City and still be an American. Similarly, you can be part of $hacking_organization and be an Anon. Or you can not be a hacker at all and be an Anon.
If you're going to start pointing fingers on the net (or throw things at those who do), starting from a point of understanding the primary cultures helps.