When going through the low-quality posts review queue, I am often confronted with posts which are indeed quite low-quality. Usually they are valid posts which are not really eligible for deletion (for example, they attempt to answer the question, albeit not very well), but they also don't "Look Ok". I believe that it used to be possible to review a post by downvoting or leaving a comment; however, this is no longer an option (voting is not even possible from the review page, and comments do not suffice for a review). The only options are "Looks Ok", "Edit", "Recommend Deletion", and "Skip". The answer does not look ok; however, deletion is not really the correct course for many of these posts. Editing is sometimes difficult to do without completely rewriting or changing the answer. So what is the correct course of action for low quality posts?
Disclaimer: I haven't done any VLQQ reviewing here on MY (i'm 71 reputation points short of the threshold at the time of posting), but i do have a Reviewer badge on Stack Overflow for it, so my experience comes from there.
I now have VLQ review privileges here.
It's actually pretty simple. There are 5 deletion reasons given (comment, thank-you comment, me-too comment, new question as answer, and link-only answer).
The first four reasons are pretty easy to tell. Confusion often arises about link-only answers. The general test is to see if the post can stand on its own if the link is removed.
If an answer honestly tries to answer the question, then it looks OK. It might be a bad answer, worthy of being downvoted, but that's for outside the VLQ queue.
For the canonical MSE question about what is an answer (to keep), see Your answer is in another castle: when is an answer not an answer?