For this type of requirement, you can do a few things.
If using Campaign Responses then this field Bounces will automatically come back into the custom field we create called bounces for all marketing automation solutions we support today.
If "bounces" goes from 0 > 1 > 2 then you can assume it is a hard bounce form the Campaign History.
MailChimp's API also supports mapping back "Hard Bounce" to Salesforce in Step 4 of your Sync Profile.
Just run a report on the custom field "Bounces" if using MailChimp to then remove those records from Salesforce.