Ford Repair: 97 Mercury Sable - rust trouble?, rear wheel wells, mercury sable

Question
Hi Dave...
I feel really stupid asking this question, but here goes:
I have a 97 Sable, bought used in Dec. 2000, now has 55,700 miles on it. Aside from brakes that sound like they're tearing themselves apart in stop-and-go traffic, the car's been great.
Early in October, I had the car in for its annual state inspection... same place it's always gone, and I trust the shop. It passed inspection no trouble, but a comment from one of the mechanics has me wondering.
He didn't show me exactly where, but according to him, the floorpan is starting to rust out on the underside of the car. His comment was "Sell it while you can... I give it a year before your seats rust out from under you."
I can't see any rust anywhere on the car aside from a small spot just starting on the inside of one of the rear wheel wells. I've NEVER heard this kind of comment made about any car I've ever owned.
I'm fairly sure this guy's just yanking my chain. The car has been pretty reliable in the four years I've had it... not to mention that I LIKE this car. But... how can I tell?

Answer
First, the brakes shouldn't "sound like they're tearing themselves apart in stop-and-go traffic". A little brake noise is normal when the brakes are hot or wet.  The brakes may be glazed, or have a low quality pad/shoe installed.  As for the rust, the vehicle has very low miles, so it sat undriven for a lot of it's life.  When a vehicle is parked, moisture develops on the undercarriage and doesn't dry off, as when regularly driving a vehicle, and it penetrates the metal.  Most parts under a vehicle, including the floor pan, have little protection or are completely unfinished metal.  I would not be surprised to see the entire undercarriage covered in surface rust.  If the rust is "surface rust", it may look a lot worse than it is.  You could have the vehicle undercoated, and SLOW the rusting.  If the floor pan is deteriorating, it may need to be repaired before considering the cost of undercoating.  I doubt the 'seats will rust out from under you in a year'.  Really, the only way to find out if the rust is a bad as this guy says, is to inspect it on a hoist.

I hope this helps,
Dave