How to trust someone to work on your car?

I got new tires today on my Honda at a tire place. I go there all the time and they have always been honest with me. I've been going there for various things for nearly 20 years. They did an alignment with the new tires.

This evening I had to take my Honda to the dealer for a recall notice. As I was checking in at the desk I saw some guys outside with my car putting things on my wheels and then he took them off and came in with a print out. The guy behind the desk said "oh boy, you need a front alignment!" I said really? I just had one done today! He blinked at me and sat there, then he asked where and I told him and he gave me the paper and said "take this in and show it to them."

How do you know who to believe?

AH! To be honest, that alignment check thing the dealership used isn't accurate. We have one at our dealership as well & it doesn't actually match the readout on a vehicle like the one we use in the back that actually does do alignment printout.

Also, it also will show rear camber/caster out & on a bunch of cars, there's no adjustments for some of those so no matter how badly you wan it aligned, we can't align it even though their little alignment checker will show it come up as out

I wouldnt worry about the alignment check the dealership did, they aint accurate at all

You think they've been honest all along. Maybe they were, maybe not, until you find something not right. Or they have new ownership, or new management and doing things different. Maybe just a bad worker.
In the future, when a car place recommends something that is a surprise to you, don't immediately agree to anything without getting a 2nd or third opinion. You may also want to do searches for the company-reviews. See what people have to say. If there's only 1 bad review, take it with a grain of salt. May or may not be the whole story.
There may also be web sites that give recommendations for car or tire places for your town. The internet has a lot of information. Use it.
I do recommend going back to the tire place and see what they have to say about the readout. My guess is the dealer is right. You paid for the alignment, the tire place should make it right.

You believe the guy at the dealership. They have enough customers that they wouldn't bother swindling you. I'm not saying your mechanic or tire guy is lying but perhaps someone didn't bother doing them at all.

If the dealership guy gave you the paperwork to show them, then he has nothing to hide and is simply helping you inform your tire guy that a mistake was made (or nothing was done at all and they took your money).