I personally don't support a global ban list, and I'm fairly certain Badspot would not either. Regardless of if a person was banned from 50 servers for being a troll, that doesn't mean they should be automatically banned from other servers where they don't intend on trolling. Plus, what if someone who regularly visits your server is on that list and you enjoy their company? Now the entire list is pointless because of 1 disagreed upon entry. I think Drama is the best solution, server hosts can see what kind of people they should be more weary about without instantly banning everyone who's ever been drama'd. I'm also against straight-banning people who you see a drama topic about, you should just be more vigilant if that player joins your server. They may intend no harm.
Coming from someone who's bought multitudes of keys, we find ways around that. Purchasing them all on different emails generally works, but swapping around payment information helps too. It's hard to attribute unused keys to people that don't want to be associated with them.