We went to the Hotter than Hell 100 just to look around and take in the scene since we had never been. In the vendor area we found a bike (Jamus Citizen) that my wife liked and the price was great. The vendor said he was from Houston and going out of business. Being it was a bike shop I figured it was assembled correctly so we bought it. We got it home and my wife tried to ride it. It would either not shift at all or skip a gear on the rear. The front would shift but the chain rubbed nearly all the time. I figured out they just threw it together and didn't adjust anything.
Being a pretty fair mechanic just not a bike expert I downloaded the adjustment info and started tinkering with it. In a little while I had it shifting like butter and she now likes it.
Moral of this story is if you can't or don't want to tinker with your new bike buy it from someone who will take care of you.