Jimbo, you need to make sure you do the right prep and checks prior to the car going out, a new MOT and PDI. My cars are mot'd and independently PDI'd. If there are faults, I state them in my video and the invoice / PDI as it forms part of the contract.
The way I see it is very clear, I tend to sell cars which are prestige, high mileage and 10+ years in age, with this age of vehicle "wear n tear" should be expected and the expectations should be very very different to newer cars which haven't been to the moon and back.... The CRA works on a sliding scale, age mileage condition and price paid and the expectations should be befitting of the above.
At the end of the day a car is just a machine and they can break at any time, irrespective of whatever prep. My job is to make sure the car is right on collection and that the customer is happy and confirms this in writing. I also educate them that anything that constitutes "wear n tear" is their responsibility to repair.
I do not offer a warranty / insurance policy, because you are just asking for endless hassle. To answer your question, if I have a problem customer within 30 days who has ignored the above, I tell them to return it me to me for a "statutory inspection" with the reiteration that "wear n tear" is not covered. It's all about expectations and education, if you are transparent and explain your stance and your reasoning behind your stance they will respect you.....