EDIT 3 Added a picture as a "proof" of what's going on (which may help other users catch such "advanced" voting rings):
In a twisted and weird way, now that my question has gotten 20+ upvotes here on meta, I was doing more edit reviews on SO and got this, from the same user which I know is gaming the system. The really sad part of the story is that there are already comments to this question saying: "I see nothing wrong". Yet everything is wrong. The entire account is fake and new accounts are create endlessly just to pump it's reputation up. And while doing so they're spamming SO (and Google) with poor content.
Take, say, the last paragraph (the other edits are golden too) in the original question (from a new, shill, account)...
Before: "how do i rename uploaded file name?"
After: "how do i rename uploaded file ins this II being whitespaces name?"
This is more than vandalism: it's gaming the system. Note that I'm sure that the new account is created by a shill: to accept edits and/or to accept the answer.
I don't know enough how SO works, but I can clearly see that this is not a valid edit. I've never been into "gaining SO rep" (4K rep on SO) and don't care about "Internet points". But I do care about the quality of the questions and the quality of the content of SO.
These fakes, ultra-low quality questions / answers are spamming SO.
The very reason I wrote "ultra-sophisticated" is because I knew there were going to be people looking into that account and saying: "Nothing to see here, move along, seems legit".
I see more and more ultra-sophisticated voting rings and they're getting scarier and scarier in that they are quickly gaining lots of rep.
It's always the same: I'm doing some edit reviews on SO (I've got about 4K rep on SO) and then notice some kind of vandalism. I don't know why the vandalism is done as these people seem to try to gain lots of rep quickly (sometimes with accounts created quite a while earlier) but I notice many shady things. I think I notice the vandalism because the edit is not actually vandalism but a way to quickly gain a few rep when the account relatively is new. The point of the edit may be to make tiny edits, change them a bit, and have several people (?) each gain 2 rep (is this even possible?).
Here's the typical scenario:
an user (very often a new user, with not even 20 rep) asks a stupid question which contains an obvious mistake: a field which is not final, a cast that is not correct, etc.
these questions are often downvoted or off-topic / on-hold (but they're probably also upvoted by the voting ring)
one or two user(s) answer basically a silly answer: "you're missing a final field", you should cast to ImageButton instead of Button etc. Note that the answers can be quite long and may be prepared in advance (more later).
the two, very poor, answers get several upvotes (probably upvoting themselves).
many "love" comments are made between these user: "I upvote you", "thanks, I upvote you too, every correct answer deserves the upvotes".
these users often answer the same questions or, at least, the same type of questions (poor questions, typically made by new accounts)
the english is ultra-poor (I'm not a native english speaker btw)
the questions and the answers do contain the same punctuation mistakes
What seems typical is that they're answering users with very low rep. What is nasty is that it seems to be mixed with real answers once in a while.
While I was writing this very post on meta (but I delayed its posting to get more "proofs"), here's an example of what happened (if that's not crazy, I don't know what it is):
a user with 1 rep asks a very low quality question
one of the account I was suspecting of fraud / sock-pupetting / voting ring answers the question less than one minute after it was asked AND gets three upvotes in less than one minute
question gets -2 downvotes
The fake account doesn't care: its answer is going to get accepted anyway, despite the fact that for some of these fake questions there are several other answers, including answers by regular users with 2K or 6K rep etc. and their answers are not getting accepted.
Now I hesitate to post the account, because I suspect that most people will look at the account and say: "Seems of poor quality, but it's still legit".
Yet there are dead giveaways, including the same punctuation mistakes made both by the account answering the question and several of the new accounts asking the questions. Namely using "," instead of ":". The very poor english is also looking quite similar: I'm sure it's the same person answering the questions and creating most of the new accounts asking these questions.
I'll post one of the account anyway but I know many people will say there's nothing wrong, because the questions look scaringly legit (they're not: most of them are made up question with the sole purpose of allowing one of the account to quickly gain rep).
Here's one the account... If it's legit I'm the queen of england and, sadly, I know many people here will think I'm the queen of england. That is precisely the reason why these rings are getting really scary.
EDIT removed the link to the user account
Just open the 16 answers he made and look at all the questions and all the comments between the person asking the question and that one answerer. This is not legit.
Most questions are poorly written, most are by new users, several have answers from other users with more rep yet it's the answer from that sockpuppet who's accepted, several questions are flagged as off-topic, on-hold, have downvotes, most have the exact same poor english and same punctuation mistakes.
That's 506 rep for a new account in a record amount of time (top 0.79% this week for answering poor questions, nearly all created by new user accounts and all sharing the same "style"). I believe the ring has users with way more rep than that and they're able to push new accounts reputation very fastly.
Note that this is just one account: in addition to most of the fake new accounts, there are also other account with quite some rep in this ring IMHO.
My "question" on meta is just what not to do with this particular account but what can be done so that these very sophisticated voting rings don't gain as much rep as fast.
EDIT 2 I noticed that there's also sometime a little delay between the answer and the acceptance of the answer, but it makes the fraud even more obvious: the last answer accepted (which I noticed just got accepted) for that user was on a question which had four answers (basically all good and equivalent). It's of course the one from the suspected account that was accepted by the (fake) new user account. That's the case for many of the question he answered.