I wasted some time at the music store the other day, making low-frequency noise on basses I can't possibly afford or justify given my lack of talent. As I plunked away, it seemed like every instrument I picked up just felt wrong, despite being some pretty amazing pro-level stuff.
The issue? When I played enough to be a snob, I would have called it "guitar player setup": super-low string action resulting from a tech who's used to six tiny strings instead of four big fat ones. Like most generalizations, this one isn't fair -- plenty of bass players like low action, and plenty of guitar players can set up whatever action you like. But when you come over to electric from upright (which generally has action high enough to drive a truck under), that "just buzzing the frets" feel will drive you nuts. And -- right or wrong -- your first thought will be, "This place has no idea what they're doing."
If (unlike my wife) you're still reading, you're probably wondering just what the heck all of this has to do with bikes. Simple: When you look for a mechanic, find one that rides what you ride. An example: At the first shop where I worked, we sold entry-level BMX bikes by the truckload, as fast as I could put them together. I never rode BMX as a kid (much to my chagrin, my parents bought me a banana seat bike instead) but I figured it was no big deal to set them up. One speed, a couple brakes, easy peasy.
As business picked up, we needed to hire another mechanic, and a lanky, long-haired dude named Ryan applied. He was an MTB noob, but had actual BMX skills, which he once demonstrated by bunnyhopping his vintage GT Performer into the bed of my pickup truck. The first time Ryan saw me putting a BMX bike together, you'd think he'd witnessed me taking a magic marker to the Mona Lisa. If someone really wanted to ride that bike the way it was intended, he assured me, pretty much everything I was doing -- from brake lever angle to chain tension -- was wrong. He quickly undid my assembly, and walked me very slowly (as if explaining to a three-year-old) through the proper setup, explaining why each adjustment needed to be just so.
So the next time you're at the shop, check out the employee bike rack (if the employees don't bike to work, just turn around and leave). Do you see bikes that look kind of like yours, or kind of like the bike you think you want to buy? I'm not talking about those little personal quirks that are unique to each person's bike. But if your thing is road bikes and all you see in the rack and/or on the sales floor are full-suspension MTBs, you might be in the wrong shop. Sure, a great mechanic keeps his or her skills up to date on everything, but there's nothing like the knowledge that comes from actually riding the equipment you sell and fix.