I believe this isn't common knowledge, despite the fact that it's fairly obvious. The trade boost trait for the Uesugi clan does nothing in vanilla Shogun 2!

It is supposed to increase trade tariffs by 5%, however the only boost you get as the Uesugi is the 3% from the naval tradition building. You can easily compute it by comparing with the tariffs that the Yamanouchi or Ashina clans get in turn 1 by trading with the Uesugi. You can also notice that the Otomo get exactly the same 3% trade boost (from naval tradition in Bungo).

I think it's common knowledge that the Tokugawa/Hattori traits are bugged, but I've never seen someone mention this, until I came across this mod:


The creator of the mod does an excellent job of explaining the bug in the comments, and the mod works exactly as intended. Huge props to him for noticing this bug and fixing it! In fact, the same person seems to have fixed some other bugs that are hard to notice in his other mods. I recommend checking them out.

I think the general consensus about the Uesugi is that they have decent traits but a rough start in the campaign. I was very surprised to find out that their trait is actually bugged. It's a minor boost but it might be a good time to replay the Uesugi and see if this makes them any better!