I think most of us use neutral tags for this sort of things, even if it was implemented for other purposes..
It is poor use of the feature and should be discouraged, but it is so common for people to use neutral tags for just about anything right now.
...but you should not use trust ratings to attack a person's opinions or otherwise talk about things which would not be relevant to reasonable prospective traders.
The feature that works well in this case is the ignore button.
- Jay -