I observe this many times, some users is continuously asking unnecessary questions and also without doing any research toward the question.
Strange thing, if we down voted or flag their questions, it's imitated get fishy upvoted.
How this scenario can prevent or monitor?
Downvoting bad content is the way to go, but...
if you find strange voting patterns, just flag the question explaining the problem and one of the moderators can investigate further.
But keep in mind that false negatives may occur. I mean there can be some "upvote games" that might go undetected in the moderator reports.
If there are clear signs of voting fraud, the main user will get suspended and the voter accounts will get deleted.
If there is no evidence to support the voting fraud, your flag will get declined, but you can try again an other day if you see the same user following the same pattern.
