• Freely readable with no need to register. E.g., Stack Exchange.
• Site requires login, but accounts are generally free. E.g., Quora.
• Site requires login, accounts are not necessarily free. E.g., Wall Street Journal.
• Per article fee. E.g., many scientific journals.
• Content not actually available online. E.g., many hits on Google Books, where they have excerpts of the book online so you can find it via search, but to actually get the full content you have to by the physical book.
Users could then choose to exclude some categories from their search results, or to have some shown ahead of others.
just stop reading quora and stop clicking on quora links (especially in the google SERPs) and the problem will solve itself.
Most contributors on Quora don't know that their content is being presented this way. (According to Quora's ToS, the submitter's content is their own.)
This isn't to say I like Quora. I can't wait for someone to come along and fucking destroy them, and take their excellent userbase with them.
 For fob's sake, you can't even view their Contact Us page without signing up: http://fab.com/contact-us/
You can just paste this code in and generate yourself a bookmarklet to reveal the quora answers (should work on all browsers).
The Chrome extension is nice because it automatically executes on quora.com (and not elsewhere). Install and forget.
Here's what I see - http://imgur.com/m9G1Q
What am I missing?
Also, the first answer is always clear - they blur subsequent answers.
(I got the blur, while my friend could see everything.)
Or Firefox: http://i.imgur.com/wv7JJ.png
Expert sex change at least has the content on the page, unadulterated, after you scroll past a bunch of ad blocks. Totally different from what Quora does.