It's easy to see why this happens. After all, the one person in the world least qualified to identify the correct answer to a given question is the one who asked it.
That depends on the context though. If the person is asking a question because something isn't working, and an answer solves the problem, they are then the best person to qualify whether the answer was correct.
Though yes, if you are asking a question from a more academic perspective, then you wouldn't expect the person asking to be the best judge of the right answer.
You'll often see the first answer that comes close being accepted, even though it's fundamentally flawed and doesn't actually work.
Other times, the best answer is something along the lines of "You're approaching the problem wrong.", such as in "I'm storing customer IDs as a comma separated list in a column. How do I join that to the Customer table?"
Too many people will offer up horribly complicated solutions that technically do what the questioner asked, but the real correct answer is "Normalize your schema."
If you asked a mechanic to fix some broken pipe on your car and he used a bit of duct tape to do it.. even if it worked, would you say it was a "good answer"?
I often see the "Accepted" answer with 2 or 3 points, and then a question below that with 10+ points which has more work put into it over a longer time, so the first answer was a quick solution to fix the asker's question, but other users put work into a better answer and the answerer ends up getting points for that as well. This is great because it creates a fast answer (good thing) and a good answer that takes longer. (also good.)
As some of the comments on this thread allude to, it depends on the frame of reference. I'll assume you mean the customer is in a professional garage seeking a permanent fix and has the money to pay for it. In that case is duct tape a"good answer?" I think we both agree its not. But if the person were stuck on the side of a road and a mechanic drove by and that was all he had or if the person had no money to pay for a new hose, well, then duct tape might be a good answer (or the least of evils).
So to point out the obvious with these q/a sites, caveat emptor. One has to look at the context of the site and the question(s) asked to determine what is "right" or "wrong" and what assumptions are made, for right or wrong.
That depends on the context though. If the person is asking a question because something isn't working, and an answer solves the problem, they are then the best person to qualify whether the answer was correct.
Though yes, if you are asking a question from a more academic perspective, then you wouldn't expect the person asking to be the best judge of the right answer.