I never buy any vehicle with out a complete 'look see' by the correct qualified mechanic. NEVER. Of course the only new vehicles we buy are my wifes. All of mine are used.
And if I don't buy whatever I was looking at, I give the report to the owner so they can see WHY I didn't take the leap, as it were.
I apply this to lots of area's. Like most realtors want you to go look at a house, write a contract and THEN get it inspected. We do the opposite.
Get it inspected (we used the realtors inspector), THEN make the offer, as we stand on a position of knowledge, rather than having to 'negotiate changes' in a contract. It's just SO MUCH EASIER.
As a gunsmith, I will repair a firearm and give it back to the owner. I tell them to shoot it and if my repairs are 'up to their standards' then they owe me 'X'. Over the years, I've got only one guy who still owes me $10. But he's a street cop with three kids, so I don't expect to see it any time soon.