I recently worked on a project with a huge TM from the client. Unfortunately the TM was rubbish, but had some important terms inside.
Wouldn't it be possible to introduce a kind of temporary (project-specific?) TM penalty, e.g. giving a certain TM a user-defined penalty of, let's say 10 %? Perhaps with a ⚠ sign at the top right corner?
This would the perfect complement to the priority feature (which sometimes is not enough, IMHO). And this would be also a nice thing for better handling of MT TMs.
How about adding an identifiying and fuzzy match rate lowering string to each source segment?
Adding a string would alter the whole TM, it would not just be a temporary or project-specific change.