Quote from egingellIf I'm not mistaken, all of those addons make their own tooltips using GameTooltipTemplate.
Auctioneer does for sure and it looks like that officially goes beyond my typical "tinkering". That's fine, Auctioneer isn't something I consider important for the aesthetical aspect of the UI. I can't find that in QuestGuru or SLDT however, and those two are the important ones.
Again, thanks for the help guys.