What Mysticial said:
No action needed. If they keep doing that, they get question banned.
Moderate the question as you would normally do. If you feel you can improve it by commenting and/or editing, please do so and if you feel it's close worthy, vote to close it. If you don't feel it's useful or sufficiently researched, well... you know what to do ;)
There is a small trend of people deleting and then re-posting exactly the same question, possibly in an attempt to clear the downvotes they received when they first posted. I remember a recent conversation here on MSO (that's probably deleted now, the question was an outright rant) where someone admitted to doing just that and was complaining that they've been caught in the question ban trap because of it.
However, there are also newer users out there who don't have the slightest idea that deletions on Stack Overflow are soft or that every edit brings new attention to the question (and perhaps even upvotes, if the edit was any good). The site's mechanics and the community's culture are fairly complex and we can't really blame newer users for getting it wrong at first, especially when it comes to nuanced details. Deleting and re-posting might be an attempt to clear downvotes or close votes, but it might also be a symptom of "forumitis". In any case, the question ban will catch repeat offenders, so there's really nothing special the community should be doing.