If the post is nothing but abusive/offensive content -- that is, there'd be nothing left if you edited that out -- then flag as offensive (and vote to delete if you can). Accepted offensive flags carry a 100-reputation penalty to the poster (or last editor), which should indicate that they are for serious situations that can't be fixed through milder means.
If an answer is merely wrong, even dangerously wrong, the proper tools are downvotes and comments. People are allowed to be wrong on the internet. In severe cases you can encourage a community deletion, either through votes (hard to come by right now, I know) or consensus on meta (more attainable), but moderators won't usually delete these kinds of answers unilaterally.
If an answer is wrong and you're highly confident that the author didn't mean it -- for example, he clarified in comments but didn't edit -- then you are encouraged (but of course not required) to edit the post. That's part of collaboratively making the site, and therefore the internet, a better place. But "wrong" doesn't call for flags; fix it if you can and want to or vote and/or comment and then move on.
If a post doesn't follow our back-it-up rule then it should get fixed or annotated. We've had a lot of discussions around this and I don't think the community is 100% aligned. What I personally do depends on the severity of the situation: if I think it can be backed up but it's not currently, then I'll usually leave a comment first and give the author a little time to respond before hanging the annotation badge of shame on his post. But if I think the post is farther away from that state -- if it's just a one-liner opinion, for example -- then I go straight to annotating (or, as a user, flagging for annotation).
Aside: if a question is getting a lot of attention and you're seeing annotation-worthy answers, it would be helpful to look at the other answers while you're there. When we annotate a post we (legitimately) open ourselves to the challenge of "why mine and not that other one that's just as bad?". Try to help us out with that, ok? If I get a flag on one of 10 answers on a hot question and I don't have time right now to examine the other 9, I'll just sit on it until I have time. That delays action. Sorry, but we moderators have day jobs too; we need the community's help.
Now, about this:
To me this is the proper time to use flags but it seems that at least one of our moderators has a different opinion.
You made a recent, vague meta post about this and declined to edit the post with specifics that we could talk about when I asked you to. Vague complaints can't be investigated or discussed. Moderators are limited in what information we can reveal, so I can't post your flags and our responses for others to comment on. If you want to talk about specific flags, bring them up.
I did decline one offensive flag from you where a simple edit would have fixed the problem. I wrote you a response explaining why I did that. Did you see it? I also responded to your comment on meta.