I had used the strategy of hiring a reliable dealer whom I knew personally to check the car being sold on PWs. Alhamdulilah, he was able to identify a good deal after reviewing three cars. Two of the cars were being sold by dealers in guise of genuine sellers. The person from whom I had bought the car - I have now learned - is not a dealer and used it personally for two years but did not get it transferred. He had a milk business and was in urgent need of cash so he sold the car at the right price.
Whether buying through a dealer or a genuine seller, it is critical to get it checked by a reliable personal acquaintance or professional. Car mechanics can't identify the costly hidden faults. Even if they do they would want you to buy a faulty car as it is their bread and butter.
Befriend a reliable dealer with no history of cheat or fraud as I had done. I believe an experienced dealer knows exactly what to look for when buying a car since he has personal experience in selling so many cars. They can tell what's wrong with a car just by driving it. Mechanics are good at resolving apparent faults but not identifying hidden ones.
In 2008, I had bought a car (Suzuki Margalla) from a person who had advertised in a newspaper. The car turned out to be accidental that required a lot of repairs. At that time, I did not get the car checked by a professional dealer. I had paid my mechanic Rs. 1000 to check the car but he could not identify that it was accidental.
This time around I decided to get the car (Honda Reborn Oriel) checked by a reliable car expert and alhamdulilah it is in much better shape i.e. non-accidental. The paint condition is 100 percent original and the car has all the bells and whistles like Android panel, back camera, etc. It requires usual repairs - oil change, radiator water change, tyre, PS leak repairs, etc. But there is no major fault like engine mount, suspension, or rust issue etc.
Genuine sellers are like pearls in the ocean that are hard to find in my experience. Get an expert help to find those gems.