See also: Why does flag marking as helpful/declined not always correlate with moderator action?
Usually, when the moderator sees a flag and has to think for a while over the flag, reading the post carefully (i.e., the action that should be taken is not immediately obvious), the flag gets marked as "helpful", even if the post doesn't get closed/deleted. "Helpful" means "While it may not have applied for this post, don't stop flagging posts for similar reasons". After all, each post is different, and we don't want to discourage you from flagging a similr post (where the flag may be valid).
Besides this, IIRC a close flag gets marked as helpful on the first close vote a post receives.
Regarding your specific flags:
- Total Number of Dimensions in the Universe?: While popular science-y, this is neither unclear nor off topic IMO. However, similar questions may tend to be of the same type.
- In what order should unit symbols appear? This isn't off topic, questions about standards are OK here as long as they aren't too localized
- Could all strings be one single string which weaves the fabric of the universe? In my opinion, this probably can be closed as non-mainstream since it effectively proposes a theory and asks for evaluation. However, I'll let the handling moderator deal with this.
- Could life survive a pole shift caused by an asteroid collision? Your flag here was marked as "helpful" by Community ♦, so it got voted to close by a few users (the votes have now expired). I personally would have declined the flag: While the question does talk of a possibly crackpot theory, it is asking for evaluation of one point within the theory, and it's to a sufficient degree physical. (Of course, it would have helped if he replaced "all life" with "most life", but that is clear from the context)
- Why are we talking about space curvature as if we know what space is? You seemed to want it deleted, not just closed. There's no reason to do that; downvoted closed posts get auto-deleted anyway, and there' no particular need to wipe such posts off Physics.SE (they don't show up on the main page)