I'm not convinced this is worth the effort to clean up. Of course, any improvements are always welcome, but I think there are probably other things which are more critical to improve, e.g. ID request titles. If you encounter an answer like this in "the wild" and feel like cleaning it up, go for it, but I have a hard time believing it's worth anyone's time to actively search these out.
However, this is something that we can find relatively easily, unlike poorly titled questions. I wrote a data explorer query for this purpose (mostly by cutting and pasting stuff from other queries). It returns a list of all answers with a given tag sorted by their length in characters, and some other meta data related to them. While this could be improved by dealing with links and images better, it should be useful at least for finding the worst offenders if you feel so inclined.
With that said, a word of caution. You can certainly find most of the answers which need more detail this way, but the false positive rate is also large (probably over 50% even if you only look at the shortest few dozen answers). Many of the answers, including some with a very low character count, are nonetheless perfectly complete answers to the question which anyone can verify. If you are going to do this, I suggest focusing on the ones which need additional information to be verifiable by someone who has not watched/read the series, not just anything which is short. I also agree with nhahtdh's answer to prioritize accepted answers and to tailor edits to the question as best as possible.