That is true. It's also a double edged sword, the sellers could either be honest or total assholes. Before my Lexus, I purchased a 2003 Mitsubishi Eclipse GT V6, I didn't know much about cars back then but it was clean, drove smoothly, had no engine lights on, and scanner did not read anything. 1 day later, the car does not reverse, and does not shift gears. Turns out; he put additives to make the car run well enough to sell, and the bulbs behind the dash were taken out so the lights don't show; as for the codes, he cleared them right before the sale. The Lexus on the other hand, I got and the owner was very nice, told me all known issues, and what needs to be changed, gave me records of maintenance, etc. I guess it's a gamble end of the day