So, I'm a bit confused how the Master Trader perk is working in my game. In terms of mods, I have Dawnguard, Hearthfire, and Unofficial Skyrim Patch. I'm unsure if UKSP is changing this behavior or not. . .

I've noticed that *some* of the miscellaneous vendors (food, jewelry, innkeepers, etc) in the game get an extra 1000 gold from my Master Trader perk, but others do not. Is there some rhyme or reason to the difference?

Do I have to trade with a vendor first, then next time their inventory respawns, they'll respawn with the extra 1000 gold? Is it just sort of random - some of them are flagged to get the extra coin, and others are not? Is it based on being a Thane in the hold? Do I have to trade them up to 1000 gold pieces first, like the old Morrowind trick of selling alchemy ingredients back to a vendor to get them to permanently increase their stock of that ingredient?

Is it based upon whether I've completed a quest for that NPC?