I'm looking for advice regarding inspection of a used car before buying. I want to buy cars at auction and sell them for a profit, I work with a friend who's an expert but I want to learn and I've got some questions. I see people give advice on how to find out if the exterior is in a good condition, but then I don't know (how bad is that and if it means i should walk away or what?). Below are common things i hear as well as my questions, could u please help me with answers would appreciate it. I keep on hearing an advice that says, check VIN numb on every door, if it's not there then it was involved in a collision and part/s are replaced). Question: So there was an accident and instead of repairing the old door (which might not come right again) it was replaced by a brand new door. So why that is a bad thing? A part of the car was damaged & was replaced with a brand new part bringing the car back to its original status. Is that advice is given only in order to raise suspicion and investigate more then decide? or does it mean I have to walk away and why? I've got a car myself, it's new and i know that it's in pristine condition, but was unlucky to have 3 accidents/ incidents (it required replacing front bumper, front grill, and panel beating on the bonnet). NO mechanical, electrical, structural issues whatsoever, the accidents that occurred weren't big, and they were fixed by panel beating specialists of that car. If you look at my car now you wouldn't spot a diff between it and another one that just came from the factory. However, if you take a close look, walk your finger through space/line around bonnet, you'll feel and see that it's not perfect but that's it. Now if I come across a car like mine, had some incidents, and was fixed in the way described above, and there's this little defect in the body, should I buy or not? would that little defect bring the car price WAY down although it didn't make any damage to mechanical & structural components?