It sounds like you need tiered unsubscriptions ie. different levels of unsubscscribe rather than a one size fits all.
For example, we've implemented the following:
- Unsub product X
- Unsub Topic Y
- DO NOT MARKET
- Unsub All
This allows us to be a bit more precise with customer management - and allows leads to be removed from marketing campaigns, while still being contacted by sales via Engage.
It should be noted that we didn't use the standard Eloqua Subscription Management to do this (but it should be up to the task?) because we are integrating multiple business units at the same time and needed more flexibility.
Re: bounces ... as Jon said - if the email is a hard bounce it doesn't matter what sales think ... the email doesn't work!