This is no longer my point of view; so I changed title, removed comments and accepted Jeff's answer.
The comments on this answer made it clear to me and changed my mind...
May this question serve as reference for future similar questions, if anyone else experiences this.
The Help Vampires are often seen on our sites, but I want to state for once that the current solution doesn't work, let me explain my view on it and I hope that you do agree on this so we can do it right.
A search for Help Vampire comes up with the Help Vampire problem, let's look at this question in detail and see why the current solution is not right enough to this problem. See the top answer there...
You will see, the trend there, is to
flag, which seems like a good thing from your point of view, because it clears the activity from those Help Vampires away. Ah, clean. Right? ... No.
What will the help vampire do?
The user will either try again to form the same or a similar question in a similar better way.
Result: The same or a similar thing made shiny, but still a help vampire.
Never, ever forget, that the user sees quality in his question and does have a problem,
so he will start wondering what went wrong and eventually ask a question on meta.
Result: The Help Vampire moved to the meta.
The Help Vampire has wasted his time and goes away to try to get a better solution elsewhere or gives up, he is still a Help Vampire which doesn't have a solution and may come back in the future.
Result: The Help Vampire is gone, if he were cured he could pose great questions in the future.
So, the trend here, is that the problem isn't solved. We're hammering our community instead...
To further elaborate on this problem:
So, let me sum up what I think is the right solution:
Check for duplicates that do answer the question or that learn the user towards solving it himself;
if this doesn't exist, look through the Community FAQ or Google or start wikifying, a good example on Super User can be seen here and here.
Explain in a comment to the user, that his answer is either to broad or to simple and that he can find his answer in the duplicate, on the Community FAQ or somewhere else.
If the question doesn't take that much effort, it might be useful answering it so that in the future it can be used for marking similar questions as duplicates.
And if you have a hammer, after guiding the user, you can finally downvote, migrate, close or flag as that does make sense now to the Help Vampire. And does show him that the community would like better questions, teach him that you expect extra effort by pointing him at /questions/how-to-ask.
And if you are a moderator, you might consider to check the user profile to see if he is a bad Help Vampires which doesn't make effort to reform his questions. As those Help Vampires are a problem.
I would suggest to suspend him after a third bad question and ban him after a fifth bad question.
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