Well you do have to grill them a bit, ask what they've worked on and if you can talk to the alignment tech directly.
I did have this happen recently though. Took my '72 D200 in to a shop that had been recently bought out by a corporate chain and the super experienced tech who had custom aligned my Duster last summer was gone. Replacement guy was decent but not nearly as competent and experienced and wasn't able to adjust things to where I wanted. I won't be going back there but it's not like I could if I wanted, I moved to another state lol.