If you run this query it flags questions such as Where do our memories get stored and how are they retrieved again? where neither answer is good (-2 and -5 in vote scores) yet in this example, the -5 answer is accepted.
This example is a very old question which the self-answer was the accepted answer at -5 and the -2 answer was provided before the self-answer.
The problem I see with leaving them as is, is that bad answers lower the quality of this site. On the other hand, deleting bad answers due to lack of referencing or whatever will increase the stats for unanswered questions.
Do we actively clean up these bad answers in the hope of better answers or do we leave them?