I have heard the CMs at DTD has the most savvy regarding tickets. but that means you have to go to DTD early in the trip.
That kind of info is a "moving target" that can change within hours.
There are CMs of varying competency, training, helpfulness at any and all Guest Relations,
depending on the vagaries of days off, shift changes, reassignments, dining breaks, etc.
You can get a great CM... or a noobie... (managers included) at
any location at the time you happen to be there.
Your best defense is knowing exactly how much an upgrade should cost
(ask on this board, if in doubt) and then, at the window, if the wrong price ls quoted,
nicely ask for a manager, or nicely tell the CM you've changed your mind, and then
go elsewhere for the upgrade.
A guest's best resource is advance knowledge.