Sure they do. Good performance is a result of everything working as the engineer intends. You measure brake rotors for thickness and parallel. The machinist should be measuring too. But if he doesnt, you can. You should have a vernier available, or even that brake mic. Buy a snap gage or std inside caliper, and pull a few lifters. Measure the bore, and the lifter. If there is significant difference in the measurements, you are on the road to good performance. I hear a lot of "it's specialized" coming form various people. If you are mechanically inclined, all you need is the interest, and the right tools, and you can do it. Dont be mistaken, if things need work, there are costs associated with them. But if you can determine without a doubt the shop was at fault, then they should share those costs, or eat it entirely. If you leave it to them to check, you let them determine if they need to pay...Guess who's fault it will be in 80% of the cases?