[William Cloud Hicklin]

Yes, you're on the right track with regard to Faramir. Since he didn't desire the Ring or the power it represented in the first place, being in its vicinity was not going to change his personality or 'corrupt' him.* Jackson singularly failed to appreciate this point, and invented the whole Osgiliation based on the notion that any Man (besides Aragorn) would be on it like a duck on a June bug, no matter what his previous character or moral stature.

Boromir did desire it- from the moment he saw it at the Council he coveted the Ring, or the strength he believed it would bring him (Sam says as much to his brother). Combined with spending many weeks in its vicinity,** the desire would eventually overthrow his will, even to the point of oathbreaking and betrayal.

Denethor shared this weakness, which is why Gandalf tells him that "Nonetheless I do not trust you. Had I done so, I could have sent this thing hither to your keeping and spared myself and others much anguish. And now hearing you speak, I trust you less, no more than Boromir." It is specifically Denethor he doesn't trust: not any Man or any Steward, but this particular one.

* PJ shows this misunderstanding much earlier, with Bilbo at Rivendell. As filmed, Bilbo is momentarily transformed into a ravening little beast, lunging for the Ring; but it's very clear in the book that it's Frodo whom the Ring affects, making Bilbo look disgusting in Frodo's eyes. This moment is echoed with Sam in Cirith Ungol.

** I do think that the Ring can work without physical contact: but it has to have something to work on in the first place. It would have burned Denethor's mind away, we are told, even were it buried beneath Mindolluin: but that's because Denethor wanted it so. The Ring can only seduce the lustful.