The letter starts out by making you feel real special: "It's not every day we offer someone a line of credit up to $XYZ."
Okay, now I feel real special. I feel pride, I feel joy, I feel superior. Imagine that, someone out there really cares for me and wants to offer me $XYZ. The classic sales pitch of making the subject feel smart is in motion. I'm now only a signature away from receiving a load of money and I didn't even have to ask for it.
The worst pitches are the ones that have a check attached. It's a real check, with a disclaimer of course. You deposit that check and they've got you. How can one refuse such generosity and kindness? Of course, the rational move at such moment is to make confetti out of the letter and send it straight to the garbage can.
Would these people care if I was in dire need of cash? What if my credit was poor and I really needed the money? What if I needed a special deal? Would they be so generous then? For once, I wish they would prove their devotion by sending me a check with no strings attached. Or how about some cash with a nice note like: "We just thought you could use this cash. Just pay us back whenever you feel like it."