As an aside: I hate quora' site design so much I have blacklisted it using Google Personal Blocklist. Somehow I dislike it more than Experts Exchange (which is also blacklisted), it is just super cluttered with nonsense, rolls into the comments section without warning and rarely offers good content (see Experts Exchange again).
That being said Yahoo! Answers also rarely has good content but at least with Yahoo! Answers you can determine that with a glance. You visit the page and you can see the answer (or lack of answer). So Yahoo! Answers remains in my search results, Quora and Expert Exchange have been vanished indefinitely.
PS - Quora also likes to spawn pop ups whenever you click anywhere on the page for no real reason (just asks for your Quora login details). For someone who randomly highlights blocks of text while reading this is pure hell...