I normally encourage people to get an AA or RAC check done if they're unsure on one of our cars because:
1. It's better than their uncle/auntie/cousin/brother or mate from down the pub that knows F+CK all about cars pulling it apart [specially as its probably on your driveway].
2. They have peace of mind.
They don't normally need to drive them, although somtimes they do
Thing is, they will ALWAYS find something wrong and write it on their report, mostly to show they've checked it thoroughly to the customer.
One example was "Near Side Rear Tyre pressure low".
It was like 1 psi out
one thing I WOULD say to them before hand is, they're not getting any money off the car to cover the cost of the check.