If this trust system works correctly, it doesn't matter if someone spams or not. Everyone can define their own trust lists here. (maybe similar function as #bitcoin-otc WoT gettrust?)
It would be silly if the forums started to remove some trust ratings because 'it's spam.'
Spam that promotes a company in the trust? Think you have take a closer look at this abuse. Spam of the trust according to Theymos is not allowed. So I guess I will defer to that, unfortunately, the work required to actually police it is the problem.