With so few users on this site who can see deleted posts (you're one of only three at the time of this writing), it's difficult to actually tell you how we've been doing. It's quite common for heavily downvoted posts to be deleted by their authors and there's nothing that prevents that from happening (assuming it's not also accepted). So, if you've seen heavily downvoted answers disappear, only you and two other people (John and Crafter0800) can currently see how they were deleted... which, I think, is part of why we're asking you to give examples.
There are two main reasons that a question here would be downvoted (and some answers may meet both)
- Answer is wrong or is not supported by the community as a good solution.
- Answer is of poor quality. It does not explain itself to the level required by this site. Or it answers a question that wasn't asked (wrong location, for example)
We should never delete type 1 answers if they aren't also type 2. It's certainly good to see what other people think the answer should be and see that others disagree with that as long as the answer isn't somehow harmful - which may be subjective.
Type 2 answers should definitely be deleted. They are poor representations of what makes an acceptable answer on this site and should not be retained.
I have certainly voted to delete a few answers from the low quality queue but I've endeavored to only vote on answers that didn't meet the policy for quality, not because I disagreed with them. But, if the answers are still on the site based on your comment
I'm not necessarily talking about posts that have been deleted, but rather posts that could have been.
Then it seems like we're doing OK? If you've seen posts in the LQP reviews and you've voted to keep them and they are still here... then we're not deleting answers that are simply wrong.
So, hopefully, we'll keep that up and, if we need a refresher, here it is... and if you don't trust me, refer to this Meta Stack Exchange post on the subject.
Why shouldn't I delete wrong answers?
There are different kinds of wrong.
"Wrong" as in "completely unrelated to the question"? Go ahead and delete those.
"Wrong" as in "yes, that will solve the problem, but that's a bad idea"? Those should be downvoted. Think of it as a lesson - showing a bad solution can be helpful as well, especially if it's an obvious solution that others may gravitate towards and/or when accompanied by an explanation (say, in a comment) of why it's a bad solution.
"Wrong" as in "this doesn't solve the issue, but it an obvious attempt at providing a solution" is trickier. The appropriate action here would depend on what the answer actually was. In most cases, I would go with downvoting as well or, frankly, not voting at all.