"Very low quality" flags are quite ambiguous as to their purpose, without a whole lot of agreement. More relevantly, they're marked helpful by an edit—any edit, even correcting a typo‐often before a moderator gets around to declining them.
Occasionally, these show up as review audits, as they did in First Answers Review Suspension because of plagiarized answers*. This is unhelpful, unless we seriously expect people to be able to catch, say, plagiarism (which would be a huge waste of reviewer time—a far better solution would be for the company to integrate with a plagiarism-detection system and flag this stuff automatically).
Further, it frustrates reviewers trying to do the right thing and drives them away from reviewing, when we desperately need more reviewers.
Deleted answers should only be used as audits if there's a helpful "Spam" or "Not an answer" flag on them, indicating (in most situations) that a moderator believed that the answer was NAA†. "Very low quality" flags are problematic, as these flags are frequently incorrectly marked helpful by edits or used for reasons other than "this answer needs to be deleted."
* In this case, the VLQ flag was cast due to moderators using the flags to downvote a series of plagiarized posts without the votes being reversed. We will probably stop doing that now...but it'd be nice if we could...
† There are edge cases here, such as an answer that was NAA, but has been edited since. Ideally, it would only select answers with no edits since the flag was cast.