If someone deletes a Global bounced suppressed contact and then creates a new contact with the same email address, the status of the new contact is dependent on how it is created.
If you upload a new CSV then the contact will be marked as Bounced if you have - Admin.System.Emails.Unsubscribe Whole System enabled and they exist in any list marked as Undelivered. If you deleted them from all lists then they would be created as Subscribed.
If you were to delete them from a list and add them again to the same list then their status will be marked back as Subscribed (check the Status column) when creating.
In any case if they are a bad contact they will bounce again and if there are 2 sequential bounces (or whatever their hard bounce setting is) they will get marked as Undelivered again across all lists.
If you are trying to send to a contact that has Bounced but you have corrected or you want to try sending to them again then you can just change the status to Subscribed rather than deleting and re-adding the contact.
