Occasionally there are posts being flagged to close, the most recent one I can think of is this one, that appear to be so because of unclear writing. In their original form, these posts should be deleted and are rightfully flagged. However, the post is legitimate and the writer simply expressed himself in a poor way, changing the meaning of the post in an undesired manner that made it worthy of a flag.
The majority of the instances I encountered were posts flagged as off topic, usually because they are too broad, where the writer only intended to ask for a particular situation but ended up asking for multiple ones.
Besides editing the post after deletion, which would seem unpractical for both the website (since the post would need to be reopen) and the writer (since a legitimate doubt got shut down), is there a way to identify these posts and are there guidelines to deal with them?