[Bringer]

I and my folks are working the ground truth.
Hitting every realm we can get to and running UnitGUID("Player")

cobbled togther something quick and dirty...

and here is a sample of what I have found so far.
When we are done I'll attach data here in thread.
We should have US and EU well covered... but we are looking for help for the other 3 regions.

I hope and expect the concatenated key will be unique... since ServerID was not.

RoboGUIDsave = {
["116-Antonidas"] = "Antonidas,Player-116-06DE3C28",
["99-Arygos"] = "Arygos,Player-99-07959C68",
["106-Aggramar"] = "Aggramar,Player-106-0795A26B",
["105-Blade's Edge"] = "Blade's Edge,Player-105-0795AD8D",
["160-Azuremyst"] = "Azuremyst,Player-160-080EC1E9",
["64-Bloodhoof"] = "Bloodhoof,Player-64-096DD251",
["1136-Bonechewer"] = "Bonechewer,Player-1136-071E6B62",
["119-Bloodscalp"] = "Bloodscalp,Player-119-06DE5ACE",
["156-Andorhal"] = "Andorhal,Player-156-080EBB94",
["121-Azjol-Nerub"] = "Azjol-Nerub,Player-121-06DE4177",
["84-Akama"] = "Akama,Player-84-06FF6EEE",
["1147-Bladefist"] = "Bladefist,Player-1147-071E6AD8",
["1174-Anvilmar"] = "Anvilmar,Player-1174-096DB9DA",
["117-Bronzebeard"] = "Bronzebeard,Player-117-06DE5BB8",
["85-Borean Tundra"] = "Borean Tundra,Player-85-06FF7622",
["77-Azgalor"] = "Azgalor,Player-77-096DBEBD",
["69-Arthas"] = "Arthas,Player-69-096DBC70",
["78-Altar of Storms"] = "Altar of Storms,Player-78-096DB78A",
["70-Blood Furnace"] = "Blood Furnace,Player-70-096DD215",
["1129-Agamaggan"] = "Agamaggan,Player-1129-080EC4E5",
["101-Auchindoun"] = "Auchindoun,Player-101-07959CAC",
["71-Alterac Mountains"] = "Alterac Mountains,Player-71-096DB822",
["1129-Burning Legion"] = "Burning Legion,Player-1129-080ED090",
["1165-Arathor"] = "Arathor,Player-1165-06FF688A",
["1426-Aerie Peak"] = "Aerie Peak,Player-1426-0795A214",
["1190-Baelgun"] = "Baelgun,Player-1190-080ECCE9",
["125-Blackwater Raiders"] = "Blackwater Raiders,Player-125-06FF7468",
["75-Argent Dawn"] = "Argent Dawn,Player-75-096DBBE5",
["52-Alleria"] = "Alleria,Player-52-07F29C02",
["1129-Archimonde"] = "Archimonde,Player-1129-080EBD2E",
["78-Anetheron"] = "Anetheron,Player-78-096DB936",
["74-Black Dragonflight"] = "Black Dragonflight,Player-74-096DD02F",
["1136-Aegwynn"] = "Aegwynn,Player-1136-071E6633",
["1138-Anub'arak"] = "Anub'arak,Player-1138-071E6320",
["73-Bleeding Hollow"] = "Bleeding Hollow,Player-73-096DD1C5",
["10-Blackrock"] = "Blackrock,Player-10-09A4F8D3",
["154-Blackwing Lair"] = "Blackwing Lair,Player-154-080ECE08",
["77-Azshara"] = "Azshara,Player-77-096DBF73",
["1070-Alexstrasza"] = "Alexstrasza,Player-1070-07F29B51",
["71-Balnazzar"] = "Balnazzar,Player-71-096DCFF4",
["54-Blackhand"] = "Blackhand,Player-54-07F2B35B",
["3676-Area 52"] = "Area 52,Player-3676-07959940",
["119-Boulderfist"] = "Boulderfist,Player-119-06DE5B6D",
["91-Burning Blade"] = "Burning Blade,Player-91-0795B046",
}