Do you think mechanics will hustle you for work you don't need done to your vehicle?

My rear brakes were squeaking pretty bad… I let a male friend of mine listen and drive around the block in my car. He told me that it was coming from the rear. I listened and surely he was right. He then followed me to the shop and explained to them… They listened as well. We left my vehicle there. They called 30 minutes later and said I needed a master cylinder and 2 wheel cylinders. I called the FORD Dealership and told them what parts I needed. They explained to me that it was unusual for a vehicle to need a master cylinder and 2 wheel cylinders… This gave me suspicions and red flags. Turns out I needed only 1 wheel cylinder on the drivers side so why would I spend money that I don't have to spend. He said usually when people change 1 they change the other side but I say not if you don't need to. Turns out I don't need a master cylinder it was his suggestion and not a diagnostic.Who do I believe the FORD Dealership which is more replical or a small neighborhood mechanic shop.

That ford dealer/parts dept is full or shlt, You seem to not trust your mechanic, I say go where you trust… THE FORD DEALER, Go trust them lol

It sounds like this guy is a cheat. You were dead right on being suspicious. As a guy that would like to start my own business, people like that guy really make it hard for me to get business. No one wants to trust a small business or pay anything at all for work because of that. I think that should be considered a form of theft and criminally prosecuted. However you would have to take him to court, which is the way a lot of things turn out. FYI, if you let someone borrow or work on or leave it somewhere, you can't press charges with the police. They will make you go to court, which is not feasible and ineffective.

It is unusual for a master cylinder to be bad unless the car is older that seems a bit suspicious.
As far as the wheel cylinders go the same conditions that caused one side to go are also likely to cause the other side to fail. So you may well be doing the other side before too long anyhow and blame the mechanic when the other side goes out next year. That is why they recommend that both be done.

For no more than a wheel cylinder cost I always replace them when doing a brake job, especially if one is leaking you have to know the other side is going to go bad shortly and when it does it will screw up the new brake job on that wheel. I don't believe in just throwing money at parts but sometimes it's the wise thing to do with certain parts.

You are being scammed. Noise at the back doesn't need a master cylinder. Go somewhere else. Look on the car talk site for good mechanics in your area.

You are going to take the word of one that did not pull the wheel off? I see a huge issue there.

While it's true that when one wheel cylinder is bad their both usually changed. But what if only one was replaced the last time? Only you would know the answer to that. As far as needing a master cylinder, that sounds like a bunch of bull. Squeaking brakes have nothing to do with the wheel cylinders or the master cylinder. Brake squeak is usually caused form impurities becoming embedded in the rotors or glazing which leaves a film on the rotors. Other possibilities are shims, or anti vibration clips missing. Without knowing the year, make, model it's hard to answer your question more thoroughly but from what you've said you need to find another shop to fix your car. Dealerships aren't the place to go because they work on a flat rate pay scale and the hourly rate is very high. My advice to you would be to ask friends or relatives who they use and with luck you'll find a place that pays their tech's hourly where the craftsmanship is up to snuff and needless repairs aren't done. Otherwise look for a shop that has a lot of car's in their lot being repaired or one that you have to make an appointment due to the work overload. Master cylinder or wheel cylinder's going bad will create a spongy brake pedal or slow sinking brake pedal when constant pressure is applied, not squeaking brakes.