We should be aware that StackExchange allows anyone from the age of 13 to open an account. This means we should always be aware of the content of our posts, including:
- Bad language
- Drug & Alcohol Use
- Sexual content
I think any post that potentially includes content that directly could exceed the bounds that our 'example 13 year-old user' shouldn't really be exposed to, then first of all try to avoid that content at all, but if unavoidable to ask or answer a question - then I think using spoiler markup is appropriate.
However please note that I would consider the average 13 year old to be aware that these things exist (language, drug use, sex, violence etc) and to be able to read and learn about why movies and TV shows include such themes - so we're not in the business of avoiding discussing these themes, just potentially avoiding having such content directly in posts.
Yes, I know that everyone's opinion of that will vary - but just be sensitive to other people's point of view, and if someone edits your post to spoiler something like that, or flags it for me to do the same - then don't get upset.