This should be an interesting discussion. We have someone who is a very active contributor (AtillaNYC is actually responsible for 7.5% of our questions). However, many of the questions asked are clearly direct cut & pastes from another source on the web.
I actually have two opinions on this that I'm going to separate into two sections. I have a "technical" opinion and a personal opinion. I want to make clear what I'm suggesting the site policy should be vs what I think as a non-moderator. First, I'll address the technical opinion .
I see this as being closely related to the easy to Google topic. Overall I think it's great to have questions asked even if they are inspired by another source. Example 3 given in the question above is a great example of this. If you see a question asked elsewhere, a forum for example, please do feel free to ask it here! This is a great way to find out if the answer from the other source is really accurate, and find out even more potential answers, as well as see how the community votes on them.
That said, I don't think it's appropriate to cut & paste questions from another source. This just isn't ethical, and feels morally wrong to boot. It also raises the concern of potential copyright infringement. Is it? I'm not a lawyer, so I can't answer that.
So I say "gleaning" a question from another source is fine. However the questioner should make it their own. They should put some effort into improving the question before asking it here. We should draw the line at blatant/near cut & paste though.
Personally, I'm rather disappointed in Atilla. I've questioned the quality of some of his questions before due primarily to their brevity and simplicity. However, I just chalked it up to idiosyncrasy and appreciated the contributions nonetheless. I was actually kind of fascinated that one guy could have so many questions, and I was quite impressed by the wide variety of dishes he was "cooking".
Now, I feel cheated. "I'm baking a flourless chocolate cake", "I was wondering ...", "I..." seem to have all been lies. What seemed like an eccentric user now seems like a mindless automaton. This feels closer to stealing than "gleaning". I spot checked random questions in his history and many are direct cut & pastes from ochef.com. This makes me feel like taking my votes back, but I'm not going to edit questions just to do that (please no one else do that either).
Going forward if I find a question that is a direct/near cut & paste from another source I'm going to speak with my votes. Simple questions are great. Asking a question you saw from another source is great. Copying questions outright, and in such quantity is just lame.
For those interested, meta.math.SE has a similar topic going on regarding a user who posts a large volume of questions taken verbatim from textbooks. There are some really good answers there that may be worth a read.
One paragraph by Tom Stephens really appealed to me (paraphrased in brackets):
With respect to building a community, the more nuanced, genuine issues ... will cultivate mutual respect and provide an interesting place to visit for [cooks] of all levels. A site catering to questions stated as textbook problems will create a repository of homework problems populated by askers only, and I think there are enough sites like this out there already.