So I'm looking to buy my first car. I'm going to buy something used and have come across a dealership that sells previously leased cars. I've looked up reviews for this particular dealership and most are 4 stars or higher. The cars are pretty cheap, however most have been in a previous accident (I'm assuming that's why they're cheap) I have next to no knowledge of cars so I am going to take any potential purchases to an independent shop for an inspection. So my question is will any mechanical issues or potential mechanical issues be found by a mechanic?
Finding evidence of accident damage depends on the extent of the damage and the quality of the repair. You don't want to pass up a potential good deal just because it was in a minor accident as long as it was properly repaired. If it was a minor accident and a fender was replaced and factory parts were used along with quality paint refinishing it might go unnoticed and not effect long term reliability. You want to avoid ones that have poorly repaired frame damage or salvage titles. Also the level of the inspection is directly related to how much time you are willing to pay for the mechanics time. If possible get a list of the things the mechanic will check and add any areas you have concerns about. Ask for an estimate of what they will charge for the repairs. You can take this information to the seller and use it as a bargaining point to lower the price. If the deal is good it may be worth paying $300 for a brake job after the sale if the car is selling for $1000 less than similar cars in your area. Many dealers in my area will include the state mandated inspection sticker in the price. I generally decline the sticker and have the inspection done independently.
If you are asking if the mechanic will spot all mechanical issues with the car or any potential mechanical issues then you may have to adjust your expectations. A component can appear fine one day and pass inspection only to fail the next day. In this circumstance the only way you would have recourse against the mechanic who inspected the car for you would be if they are willing to guarantee their inspection.
Mechanics are only human beings and may miss things. They also may only be able to inspect components based on the tools, methods and time available to them.
That said, what a professional will give you is a far better feel for the overall condition of the vehicle. Also, if they do spot something then you can have the seller repair it prior to buying the car.