Automotive repairs are expensive enough -- the last thing you want to do is pay for repairs that are never actually done or don't even need to be done. Here's an easy way to find out whether that job really needs to be done: ask the mechanic to give you the old parts back.
Photo by starmanseries.
If you don't work on your car yourself -- and I'd encourage you to at least learn to handle the basics on your own -- you're probably stuck trusting a dealership or an in-and-out oil-change joint to do a lot of your maintenance and repairs. If you're getting the sneaking suspicion that those "free 18-point inspections" are really a way to propose work that doesn't need to be done, ask for your old parts back in the boxes the new parts came in.
This isn't foolproof by any means -- some parts have to be specifically disposed of or recycled, so you may encounter some resistance. And if you have a good relationship with your mechanic, there's no reason to go this route. For those other cases, the parts are your property, so broken or not, you're entitled to them. If you get the old parts you, you can take them to another mechanic and ask if they really needed to be replaced. Plus, you can tell pretty quickly how trustworthy a shop is when a mechanic backtracks on the laundry list of repairs they "can't let you drive away" without doing as soon as you pop the question.
I've successfully done this personally several times when it was especially difficult to find a qualified mechanic to handle more advanced repairs on older vehicles. Once you find a mechanic willing to give you back old parts, show you what work will be done and treats you well, stick with them. For more auto repair suggestions, hit the AutoMD link below.