Your question is open, and it got two upvotes and no downvote -- this clearly suggests that your question is not out of place. That you didn't get any answer or comment may have multiple reasons, one of them being that you didn't give a top-level tag and that the right people therefore didn't see it. What you can do is to edit your question (e.g. add a top-level tag, possibly improve the formulation etc.), or -- once you have gathered a few more points -- to start a bounty.

Assuming that by questions of "extremely low quality" you mean such which cannot be posted in good faith (like advertisements, crank posts, links to malware sites, pure nonsense character sequences), spam flags are the most efficient way to achieve quick deletion.

@Kimball: I think you are mixing here two different things -- asking a question anonymously and asking a question as a new user. -- In fact, when Bill Thurston asked the question you referred to, he was indeed a new user of MO.

I think how to deal with such questions depends mainly on how they are formulated (did the asker take the time to formulate a clear and concise question without a lot of grammar- or spelling mistakes?) and who has asked them (is it an anonymous user who has contributed only other poor questions or nothing so far, or is it rather a known colleague or an established user of the site?). The goal should be on the one hand to prevent abuse of the site, and on the other to make the site as useful to the community as possible.

@MartinSleziak: One aspect you apparently didn't mention is that while votes are private, favorites are public -- i.e. every user's list of favorite questions is visible to everybody.

Alternatively, one could take the Wikipedia approach and give the IP number instead of the user name / user_xyz for contributions of unregistered users.

Even sites which are rather not known to care very much about the quality of contributions, like e.g. Facebook or Twitter, require registration before posting. -- I'd support MathOverflow doing the same.

@MartinSleziak: Is the timeline of a post linked somewhere, or does one need to manually enter the URL to see it?

A bounty can be set on a question only after two days -- if the question hasn't been closed already by that time, it is likely not that unreasonable. Also, for a bounty the OP needs to have (and to spend) some points -- if they do this, they are usually particularly interested in an answer. When closed, the text of a question remains visible, and so does any advertisement contained therein -- so unlike spam flags, closure is not a means to remove advertisements.

Your question has 4 upvotes, the bounty is still active, and nobody suggested that your question should better be migrated to math.SE or would otherwise be off-topic. -- So why not just wait?