After 11 years, this is what the subframe looked like on my Caliber:
Yes they extended the warranty on this part to 10 years, but as you can tell my dealer thought it was fine
Otherwise, the underside of it was pretty decent especially considering it went through 11 winters in southern Ontario where they love salt/brine and I never had it rustproofed. There was some rust starting in the top of the right rear wheel well, which I suspect was because of the poor build quality around the liftgate hinges, as there was a weld flaw in there, and water would get in. That rust wasn't visible unless you put your head into the wheel well thankfully.
Otherwise, this is how it looked the day I traded it for my Cherokee, after having it for more than 11 years: