I've only had limited Marketo training, and no one to ask in the office so here goes.... Briefly we have 16 email databases and some leads are on all or just one.
When I receive the request to 'unsubscribe me from all your databases', I was trained (by someone who has left the company now) to remove the lead individually from each list and put them onto a blacklist for each corresponding list.
eg: They subscribe to 'Magazine 1 List', so I remove them from that list, then add them to 'Magazine 1 List [BLACKLIST]' which is referenced in the Magazine 1 program.
This can be a time consuming process when they are on all 16 lists!! So now I come across this under each lead name (see image), and i'm wondering if this box is ticked does it mean that lead WILL NOT get any emails from any of the lists they are on?
Yes! 
The "Unsubscribed" field will unsubscribe them completely to all emails, unless those are marked as "Operational" (which they shouldn't be, for any marketing communications).
Your current process seems like it could be made much more efficient in lots of ways.
Even if you are trying to control for more granular list maintenance (in the case the person does not completely unsubscribe) I don't see a need to remove them from the list AND add them to a blacklist. Simply removing them from Magazine 1 list should be sufficient.
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