QA/QC is not performed on every part manufactured...it starts with a percentage of a run and if the tested/inspected...there is a difference...part/parts pass the lot is moved on. If fail then more are tested/inspected perhaps to the point of 'failing' the entire lot which then goes to a supervisor/manager and/or engineer to decide the lots fate. Usually all parts are tested/inspected and the 'passed' parts move on while the 'failed' parts to back for either repair or scrapping.

The bike shop, where I work, inspects all wheels we get and generally they are fine.