I really have to agree. I do not think that the vendors realize it actually makes them look bad when they are not participating in the forum in a helpful manner. Promoting your business is important but it is also important to do it in a helpful, tactful, and appropriate way.
If you see a vendor violating the rules, please report their post (there is a report link at the bottom of the post) so I can send a warning to the vendor.
I am sure their intention is not to alienate the members of the forum because it does not help their business.