I noticed there are some useless tags in trac tickets and listed all of them below. The only official guideline for the use of tags which I know is [PATCH]. Also [ATLAS] and [NEEDS INFO] are used, but they can be also accessed via the component and resolution filter (which also include many tickets where the tag is missing). There are also many tags which are only used once. AFAIK tags are used to mark a category / group of things, not single ones.
Now the problem is that ticket summary changes will spam the IRC channel. It could be done between around 02:00 and 06:00 UTC where there usually are no conversations. I could do it if you allowed the cleanup. Perhaps there are also some unofficial guidelines I don't know. Perhaps you also think this is totally useless though I think cleanup is never a bad thing...
[Art] x 1 - remove because you can also filter with Art & Animation
[ATLAS] x 50, [Atlas] x 8 - remove because you can also filter with Component is Atlas editor, alternatively add the [ATLAS] tag to all tickets with the respective component
[DEFECT] x 1 - remove because you can also filter with Type is defect
[ENHANCEMENT] x 1 - remove because you can also filter with Type is enhancement
[Fixed] x 1, [Solved] x 1 - remove because you can also filter with Resolution fixed
[i18n] x 1 - remove because you can also filter with Component is I18n & L10n
[NEEDSINFO] x 13, [NEEDS INFO] x 83, [NEEDS MORE INFO] x 1 - remove because you can also filter with Resolution needsinfo, alternatively add the [NEEDSINFO] tag to all tickets with the respective resolution
[PATCH] x 1058 - leave as it is
[PATCH READY] x 1, [PATCH / DISCUSSION] x 1, [WIP PATCH] x 1, [PATCHES] x 1 - rename to [PATCH]
[Petra-AI] x 1 - remove because you can also filter with Component is AI
[REVIEW] x 1 - remove because you can also filter with Keywords contains review
[SOUND] x 2 - remove because you can also filter with Component is Music & Sound FX
special tags (do not use as a tag because there is usually only one or two tickets using it):
[ATTACHED] x 1, [BUG] x 2, [Copy & Paste] x 1, [CRASH] x 1, [CRASHLOG] x 2, [Formations] x 2, [FreeBSD compat] x 3, [Git] x 3, [Information Leak] x 1, [Integrated graphics] x 1, [Mac OS X] x 2, [Mac OSX 10.7] x 1, [nvidia linux driver bug] x 1, [OOS on rejoin] x 1, [PERFORMANCE] x 1, [Premake] x 1, [Proposition] x 1, [Step 1] x 1, [Step 2] x 1, [Step 3] x 1, [spam] x 1, [STEPS TO FIX] x 1, [ Testudo / Syntagma not working] x 1, [Typo] x 1
no actual tags and/or not at the beginning of the summary (x 1 each):
[0], [2], [7341], [br], [j], [p], [pre], [shipId], [SVN], [-Wempty-body]