A "banker" is something you can bank on i.e. something you can rely on, producing the minimum loss/wastage (saving your "monies") while at the same time giving you the best bang for your buck.
Customs Officers are gonna tell you basically everything in their "work" seems to be about "dirt". About the various facial tell-tale signs they look for. And also how women drug mules, when being pulled over, pretend to faint in a final form of escapism.
She's neither sweet-tasting, nor potent enough to be cut with anything else (let alone sugars). But all Jane's must be about Mary lol. That's not sweet. That's just OCD. See your counsellor immediately!