Let's take a look at Quora's case. Please do the following:
1. Open your mobile browser.
2. Ask a question on Google and add "quora" so you get some results.
3. Open Quora's result link
4. See that result for a brief second and
5. Be forwarded to registration page, which doesn't have any close or cancel out buttons.
6. Try tapping back and you are back to Google results
7. Curse at Quora and never tap on their results again.
That last point is only for me. There is a choice to register. You are free to choose.
PS: You are right, the information that Google showed/indexed is there on Quora. But for regular people (not Google bots), it's there for a second. IDK about you but I'd place this behavior into dark pattern UX book.
For a short(?) but wonderful period of time it was possible to blacklist sites from your Google search results. As I recall Google moved this functionality into the Chrome browser several years ago.
When it was still available as an account setting I used it to filter out the awful "resources" like expertsexchange and that one Oracle consultant site with the hilarious pictures. When I see Quora results I long for that feature to be returned.
I remember that one because of the offer to learn Oracle during a cruise, complete with the important part "Convince the boss" : http://www.dba-oracle.com/BC_cruise.htm
Theoretically 6 & 7 should be a big red flag (the biggest possible UX red flag) to Google regarding the specific Quora page visited - I know that I almost never see Quora results in search, for example.
Following Bartosz Goralewicz's post about how well botting works to manipulate Google in...2014 I think? there's a small black hat industry that's sprung up around imitating this kind of user reaction, and it does reportedly work to remove pages from Google. I've had my suspicions that it's been used against sites I've worked on a few times (2 or 3).
TL:DR; Quora should generally not be ranking so well (but Google's complex enough to be unpredictable on a page-by-page basis these days).
I'm not seeing that behaviour at all direct from Google. I do get the registration overlay if I subsequently click another Quora article page from the original Quora article. The behaviour I'm seeing is reasonable, if slightly annoying.
I do not see steps 4-7. After 3, I stay on that page. Sometimes in the past I would see an overlay on that page. I don't get redirected anywhere, and I'm 100% sure I never was (there was only popup). I wonder where's the discrepancy coming from.
Also, google bot would be redirected too, unless of course it's simply logged in :)
I could make lots of guesses why you don't experience Quora the same way I do. None of that would change the fact that I can't see the information I am being promised to see on Google.
Here is a screenshot of the page I am being forwarded to automatically: http://pho.to/Aatuj
It is a disguised register page because after you make 10 selections, you are forced to sign up.
That's because you got fooled into making an account. It's trying to get you to complete the registration process so they can pick questions to show you.
If you clear your cookies and go from a Google search result to Quora, you can read the answers on the page that you're on. If you navigate to any other question, say via the links at the bottom of the page for similar / related questions, the answers will be blocked by the signup popup.
If, instead of signing, you go back to Google and search for the same "<question> quora" it'll work again. The thing to remember is only the first page you navigate to from Google will display properly.
That's because you seem to be halfway through making an account and they want you to finish.
The actual behavior of Quora, if you aren't midway through account signup is:
if you go through Google search it shows you the page promised.
If, from that page, you click on another question it will open the second question but give you the sign up modal. You can bypass a signup modal and get the normal page by appending ?share=1 to the end of the URL.
I don't even have a Quora account but I read the ?share=1 trick a while ago on hacker news.
I saw your video. It looks like you are in the middle of a, probably accidental, new account signup. Maybe you let your kid use your phone weeks ago and she did it. If you clear your cookies then you should get the behavior above.
I don't "expect" users to do anything, I was sharing a known workaround in case anyone was interested.
EDIT: I just created an account to see what happens. You are logged into a new account. Maybe you accidentally logged in with Google?
I created a new account with a fake name and email. No email verification. After the fake name and email is entered they ask you to follow topics (which is the screenshot you are seeing) and once you pick 10 your account is "complete" and they will let you look at the answer.
When I made that quora complain before, HN readers are kind enough to show me how to avoid it. Without the ?share=1 trick, I probably don't even know how Quora looks like.
1. Open your mobile browser.
2. Ask a question on Google and add "quora" so you get some results.
3. Open Quora's result link
4. See that result for a brief second and
5. Be forwarded to registration page, which doesn't have any close or cancel out buttons.
6. Try tapping back and you are back to Google results
7. Curse at Quora and never tap on their results again.
That last point is only for me. There is a choice to register. You are free to choose.
PS: You are right, the information that Google showed/indexed is there on Quora. But for regular people (not Google bots), it's there for a second. IDK about you but I'd place this behavior into dark pattern UX book.
PPS: For people, who don't believe this behavior, you can see the video of my experience on youtube: http://www.youtube.com/watch?v=xiOMwRwXLcg