There are some recent beatmaps such as https://osu.ppy.sh/s/298996 and https://osu.ppy.sh/s/291155 (recently qualified but back in Pending) which got tags they're not really appropriate at all since Tags are used to find beatmaps to a song and/or artist. And not to work as a filter to determine training beatmaps, deathstream maps or beatmaps which can cause physical injury. The rule/guideline should describe that random tag should not be used and be removed, else it allows to put any random stuff into.
Beside of this point I want wish to include in the rule to not have typos in the tags, a known case is https://osu.ppy.sh/b/417144. The tag "kirisame" got mistyped by "kiraseme" and it got ignored while the ranking process, it got fixed by online tags but it still doesn't appear at in-game if I would search for "kirisame" but for "kiraseme". It's a really rare case but it's not written as guideline (perferably) so it should be mentioned beside of the first point.
Beside of this point I want wish to include in the rule to not have typos in the tags, a known case is https://osu.ppy.sh/b/417144. The tag "kirisame" got mistyped by "kiraseme" and it got ignored while the ranking process, it got fixed by online tags but it still doesn't appear at in-game if I would search for "kirisame" but for "kiraseme". It's a really rare case but it's not written as guideline (perferably) so it should be mentioned beside of the first point.
Tags may not have typos and needs to be related to the music, either artist or song. This prevents confusion while searching for beatmaps for a specific tag. Exceptions are the usernames of Guest Mapper and/or Storyboarder and the previous username.