Here are a my personal principles:

1. I prefer a tag too much, rather than one too little. Better too much information, than too little.

2. I am strongly against removing redundant tags from questions. Redundancy serves a purpose and hence I prefer to keep the command-line tag for past questions where it is relevant.

3. Tags should be edited **if they are wrong**. That means 14.04 for questions that hold for all ubuntu releases, misspellings in tags, tags for which a dupe exists,... **Editing tags out that are not wrong, is vandalism.** When a tag is wrong is an area with fuzzy boudaries. In case of doubt, meta or the mods settle the issue.


This is a matter of semantics and of 'fingerspitzengefühl'. Hard and fast rules are hard to come up with and to enforce. Some 'don't worry, feel happy'-style is needed.

I am also in favor of **a broad tag**, but that does not mean everything slightly related to the CL should be bombarded as a command-line question. If it is important for the question, it should have the tag, otherwise it can perfectly live without it. I mean a question with rm does not necessarily need the tag command-line (even though nothing is against it having the tag! 


For past tags: let's not go edit crazy. Deleting tags is really not the most important things to do and it tends to get a bit on my nerves when tags are deleted for the fun of it. Our attention sould be more on barely tagged questions and on tags with synonyms.