Half of my duties involve doing all the certificatoins for the used car lot at out dealership. There is a litany of items that need to pass, around 180 or so. I'm not going to list them all, but here is the short of what I look for every day:
-Everythig has to work. I know that's a broad statement, but thats it. All the little gadgets, lights, accessories, levers, switches, engine mechanicals, so on and so forth. If anything is broken, missing, scuffed, or scratched, I replace it. And, all four tires have to match with 5/32" tread remaining.
-I check under the valve cover for sludge. This is a particular item of note on the 1MZ-FE V6, as everyone here will tell you.
-All recalls must be complete.
-Accident damage. Here are the specifics - the car cannot have any more than 3 body panels (excluding bumpers) repainted "by standard bodyshop practice". This means that if three panels were just blended to cover up a big scratch, it would pass. But if three panels were missing VIN stickers and had tape marks around the edges, it is not eligible. Frame damage of any kind is a disqualification. Same for flood damage.
Personally, I think we sell nice cars at my dealership. The average bill per Certified car is around $1000.00, and I kick about 20% of the potential canditates to the curb. I do enjoy knowing that folks who aren't real knowledgeable about how to get a nice car can get a good one after I'm done sorting them out.