Dear its not only the matter of reducing the value/price of the vehicle or verification or mis-trust on the seller. There is also a risk associated with it that the original book which was lost can be used by anyone for any bad purpose. Like if someone founds the original book and uses the registration number, chasis number and engine number on any other vehicle and if that vehicle is used for any negative purpose, then who will be held? that person who did the negative use or the person whose name is appearing in the original book and ultimately if you bought that car, in ETO's record, you will be the owner. So just to avoid any type of inconvenience at later stage, it should always be the preference to buy car(s) with original documents.