Email asked me to weigh in on the situational application of sponsor debt.
Sponsor debt is about using a magical conduit to an Entity of Power to pay costs you don't want to (in game terms, fate points and consequences, really). Whether or not that Power is willing to pay that cost for you depends on the terms of your "contract" as it were as represented by the agenda and how good you've been about paying off that debt.
This is primarily applicable to spell casting, but in my mind and at my table needn't be strictly sk on a case by case basis. But when coloring outside the lines like that, I'd say that taking on debt is an overtly magical act, perceivable by those who know how and what to look for. So sure, maybe you're having that Dragon pay a fate point so you can do better on your roll to appraise the value of a foe's assets. But your foe's spider-sense will probably tingle when you do that.
Folks shouldn't use this as a carte blanche thing to cover all possible actions, tho. How far you can color outside the lines and in what ways (and with what skills) should be explicitly discussed and settled upon when you establish the sponsorship. Nor should it be a substitute for taking on additional appropriate stunts or powers if you're going to pursue a particular kind of ninspellcasting thing regularly. Buy the supernatural senses if you're going to be able to sniff out wealth regularly, Draco-boy.
At least that's how I'd roll with it.