A little story:

When I worked in a LBS we did the service for the department store bikes that were too messed up for the staff (16-yr old kids who assemble barbeques) to fix. The bikes were such crap that we cancelled the contract after 6 months or so. There was no way we could (in good faith) send those bikes back out without a complete rebuild (and throwing 1/2 the parts into the trash).