Hey Jennifer -
What you should do is create a smart list in the Lead Database named (for example) "Global Exclusion List".
Then add the following filters. Use the logic (ANY)
Unsubscribed = True
Blacklisted = True
Email Invalid = True
Marketing Suspended = True
Email Address (is empty)
Then on your smart list, add the filter "Member of Smart List" (not in) Global Exclusion List. This will exclude any of the people who would be blocked from mailing.
The problem with suppressing anyone who has bounced from an email is that a lot of bounces are temporary. Send too many emails to one company, some of them bounce, but the next time they go through. Just bouncing once doesn't mean that a lead can not receive further emails. Instead once Marketo has determined they bounce too many times they set the "Email Invalid" is true flag, that's what you should filter on.