Wtf is with Quora?
 

It's a great site but I never registered with the site - all of a sudden a few months ago I begin to get email/spam from Quora every day and when I click the links in the email I find I'm logged into Quora with a Facebook account I set up long ago and really don't use.

More like: Wtf IS Quora?

Oh... ""Quora is your best source for knowledge.""

;-)

Bing and other sites are showing me as logged in when I haven't logged out of Facebook and the Facebook login box is being used by a growing number of sites.

It has been suggested that such data will (in part) drive next gen age verification for adult

maybe you allowed them somehow in past to add you