Often, while I'm working on someone's bike in my garage, they're looking over my bikes.
I tell them, generally without looking up, to "go ahead, ride whichever one you want."
In a mercenary way, I have their bike captive. In another way, it's just a bike.
One guy was gone an hour, with flipflops and cargo shorts, on a Soma Competition with lugs, Kuwahara tubing, Arabesque, and a B-17. He came back, spied a rear rack along the wall, and an hour later, we got back from another "shakedown" ride and he took it to the Outer Banks, where he spent the summer sleeping on a hammock, working at a snowcone shope, and taking the Soma up and down the Outer Banks. Over time, I've replaced the front wheel, one set of pedals, and I think he still has it. Some "loaners" are meant to be. Last I heard, it was in Asheville, where it fits right in.
Nothing says "welcome to my world" like the nearly unconditional belief that, once they're on a bike, everything will be OK. Infectious.