With - I admit - a lot of effort I have figured this one out.
I checked tons of links, many more than I posted here (I got tired of posting examples after a while) and it all checks out. It's kinda complex but here it goes:
- If there are 0 answers, google will count the number of comments of the question
- If there is only 1 answer, google will count the answer + the number of its comments
- If there are more than 5 answers (the max number of non-hidden comments) and less than 30, google will always get it right
- If there are more than 30 answers, google will always say 30 answers
- If there is more than 1 answer, and no accepted answer, google will get it right
- If there is an accepted answer, more than 1 answer and less than (or possibly equal to) the-number-of-comments-of-the-accepted-answer answers, google will count the accepted answer + the number of its comments. Else, it will get it right.
(Note: When I say "number of comments" I always mean non-hidden comments, so up to 5 max)
My suggestion to the development team to "fix" this - if they want to fix it, it's not their bug - is to hide comments from google. They supposedly don't contain important information, anyways.
Even better, change the post container from
<article> so that the comments are included in the
<article> tag, although I'm not sure it will work it's worth a try, and is more semantically correct.
Examples of questions with an accepted answer, and a low number of answers
Google # - Real # - Comments of accepted answer # - Link
3 - 1 - 2 - http://gaming.stackexchange.com/questions/39644/skyrim-will-not-launch
1 - 1 - 0 - http://gaming.stackexchange.com/questions/38928/i-have-a-huge-bounty-in-skyrim-how-do-i-get-rid-of-it
2 - 1 - 1 - http://gaming.stackexchange.com/questions/39468/skyrim-launcher-brings-up-uac-dialog-and-never-launches
6 - 1 - 5 - http://gaming.stackexchange.com/questions/38985/do-power-attack-perks-in-skyrim-apply-to-sneak-power-attacks
4 - 2 - 3 - http://gaming.stackexchange.com/questions/38809/is-skyrim-playable-in-3rd-person
6 - 3 - 5 - http://gaming.stackexchange.com/questions/38437/do-gemstones-have-a-purpose-in-skyrim
As you can see, google always see the number of answers as the number of comments + 1.
Examples of questions without an accepted answer and at least 2 answers
Google # - Real # - Link
3 - 3 - http://gaming.stackexchange.com/questions/38030/skyrim-prepares-to-launch-forever-after-nov-21st-patch
Examples of questions without an accepted answer and 1 answer
Google # - Real # - Answer Comments # - Link
3 - 1 - 2 - http://gaming.stackexchange.com/questions/37830/skyrim-doesnt-adjust-the-dungeon-difficulty-based-on-your-level
Examples of questions with an accepted answer, and more than 5 answers
Google # - Real # - Link
7 - 7 - http://gaming.stackexchange.com/questions/37473/how-to-play-a-mage-in-skyrim
Here google always gets it right (but not if there are more than 30 answers, as it checks only the first page).
Examples of questions with no answers, but with comments
Google # - Real # - Comments # - Link
1 - 0 - 1 - http://gaming.stackexchange.com/questions/39003/how-do-i-become-high-king-of-skyrim
Here the number of answers is always equal to the number of comments.