Bob,
You are exactly right, its kind of like guilt by association, you were there so you were exposed. The VA will provide any VN Vet with the paperwork to submit for exposure to agent Orange and other dioxins. Its a simple questionnaire to fill out and return to the VA. It puts you on the Agent Orange Registry.
The benefit for getting on the registry is you have the first batch of BS paperwork done. Remember that with the VA nothing is a magic Bullet.
Tom Gator 851