how much are they asking for it? considering that the new body style is in it's 2nd year ... i'm guessing $11000 for a sedan, $12000 for the coupe.
feel the seams on the car ... if there is a paint edge to it, then that panel has been worked on and re-sprayed. factory paint is completely smooth around the edges.
check the seams on the leather seats. the 6th gens have tearing issues around the area that touches your "love handles" (near the lower back, on the sides)

h:
look under the hood to see if the cruise control cable is tucked UNDER the radiator hose. if it's over, it's a sure sign that the radiator was replaced. (that's the way it is on the V6's that is)