I agree with all of the above and I would like to add:
-Cars can kind of "talk" to you. That is, they tell a story.
The harder you look, the more story you get. Whether dirty door jams or not, or a clean motor or not, these items alone do not say whether specifically the car has or has not been abused.
I take very good care of my cars and they have clean door jams and engines.
-Become a student of the subject: If I am interested in a particular series, I will start going to lots and looking at them in parking lots.
What I am suggesting is attaining a well-trained eye. Be able to spot the strengths and weaknesses. I did this before buying the 91 300E. When I finally spotted it, I knew immediately that was the car I would buy, and get this, from a distance! Yes, I inspected it carefully before actually paying for it, but I could tell it was a great car.
-It pays to get your knee dirty: An old car business saying but still holds true. Get under the car. Lean down or get it up on a lift. The most expensive pieces are rarely seen from above.
-If in doubt, check it out: Pay for an "Inspection for purchase". Most shops and dealerships do this. Usually an hour or two of labor but WELL WORTH it.
'03 E320 Wagon-Sold
'95 E320 Wagon-Went to Ex
'93 190E 2.6-Wrecked
'91 300E-Went to Ex
'65 911 Coupe (#302580)