It is mostly up to you how it will turn out in the end. Just a little mental preparation on your part can make all the difference. This applies whether you are buying from an individual or from a dealer. There are two parts to buying a car, your mental attitude and the condition of the car. Mentally, if you fall in love with a particular car and must have it, you are on the disaster track.
Most sellers are honest, but they make money only by buying low and selling high.
To survive against a good dealer you must have a value in mind and be determined to buy only if the price is right and the car is sound. Don't assume that the seller really knows the exact condition of the car, regardless of what they say. A part may break after you buy that gave no notice to the seller beforehand. Have the car checked out by someone who knows what to look for. Compression tells about the condition of the engine.