TM = Translation Memory; added by confirming segments on a CAT tools interface by usually pressing Alt + Enter or other buttons. Translation Memory functions mainly to preserve bilingual history of past translation/editing works in a small and compact format; this can be added as you go and access later to re-use.
Stupid TMs are made by stupid translators, confirmed by stupid editors, and approved by clients who hasn’t got the faintest idea that they are in the brink of creating massive chaos. You can spot stupid TMs if you got a project and the terminologies, spelling, language inside the TM are all WRONG.
How to correct stupid TMs:
1) Report to your client immediately. Avoid from making inconsistencies with the TM (ouch! Yes! You have to follow through to make progress happen!), avoid spot-on corrections. Instead, make a list of what the “wrongs” are, include the “rights” on your list (make an Excel sheet on this).
2) Go to the “Translation Memory” part, find and replace all stupidness. The method varies by CAT tools. On Trados you can make filters and repair them not only word-based but also context-based.
3) If the client disapprove of the replacement/repair, then grit your teeth and try your best to hold on to yourself as you go along. There isn’t much that you can do. However …
4) You can always place “correction” here in there, inconspicuous, some sort of a “message in the bottle” for the editors and the translators after you, so that they will see that these stupidness did not go unnoticed. Hopefully you will get it done, hopefully your Project Manager will see your points, hopefully the next translator will not scream like you did.
(I managed to correct one of my project’s stupid TM … after 4 years … keep the fight! I feel you!)