I understand your suspicions. Over the years I have seen shops and mechanics try to pull something to make a quick couple hundred bucks, both on me, and on my father when I was a little kid (going with him to the garage to get his car inspected).
Im an engineer and we frequently take photos of things. I would not get too paranoid about the one photo they showed you. When I take photos of stuff it never looks like it does with your eyes. Unless they put a ruler next to the nail head it would be impossible to guess how big it was, or if it was flush with the surface.
Also no one ever ever deletes the photos on the camera at work. Its possible they showed you a photo of a nail in someone else's tire, just an honest mistake.
Personally I have never even had a mechanic take a photo of anything to show me - ever: tires, brake pads, rotors, frame rust, tie rod boots... they just tell me: this needs to be replaced, and I have them do it or take the car home and do it myself.
It is very unusual to get a nail in a tire twice in one month. It is very unusual for the pope to die twice in one month, but it did happen. Sometimes your mind wont accept what happens and its really trying to find another explanation.
Having said all that, you do need to have a level of confidence in your mechanic. Last time I carried a wheel in to have the tire changed, I expected it would be about $40. They told me the tube looks rough and I had not bought one with the tire (from BikeBandit .com). The change was $40, the tube was $30, the balance was $10, and they charge me $2.50 for each of the three weights they used to balance the wheel = about $100. I was not happy but the shop has to make a living, and people dragging wheels in are not their bread and butter - so Im good with it.
But there is always a risk that a mechanic will screw you over. My daughter took her car to get its 4th oil change, took it to a different shop that was closer, and it still had the original factory oil filter on it. The place she had taken it the first 3 times since it was new never changed the filter, and she has no way of knowing if they changed the oil either.
Bottom line is: NO ONE cares about your vehicle more than you do. Even if you are a mediocre mechanic and it takes you 2 hours to change your oil, you will know it was done, it was done right, the bolts were all properly torqued, the oil filter was NOT put on with an impact wrench (yes! Seriously!), and while you are doing the work you will also tend to anything and everything else on the bike that you notice that needs love and care. Even if you have to buy all the necessary tools and a torque wrench to change your oil, the first time you do it instead of taking it to a shop, you will pay for those tools with the money you saved.
Working on a brand new vehicle is pure joy if you like working on machines at all. Believe me, I owned 12 used air cooled VWs when I first started driving, and keeping a rusty old used unloved vehicle running can be a real challenge.
If you are mechanically inclined at all, I recommend you do all the work you can on your bike (and cars) yourself.
Last edited by KCW; 06-29-2018 at 07:43 AM.