Unfortunately, there are many people who misuse the trust system and you can even see this in the Default Trust network. The trust system is a well-intentioned idea but poorly implemented. It would actually be better for the site if it didn't exist at all. The trust system is used for many things that have nothing to do with trading. It's full of people who abuse it for their own benefit.
While this is still somewhat true, I think its a lot better than it used to be. The current DT system is a loose but effective set of checks and balances, wherein if anyone gets too unruly with their trust ratings, they eventually find themselves off DT. One thing there is definitely too many of is positive trusts for non-trade related issues. There are currently only a few members that issue negative tags for non-trade related matters, much fewer than in previous years.