Jim, my main area of concern - as my recent posts indicate - is with the finish. Nothing I've built for my own use has displayed a problem in any respect, but then I'm pretty careful with my guitars and I'm not a working musician who exposes their instruments to mud, blood, beer and sweat (or over-exuberant groupies!)
As for what I feel I could be liable for, I would quote Allen above who makes reference to "workmanship or product failure". That's a pretty inclusive and general description, but I would guess it includes finish deterioration outside of what one would consider normal wear and tear, cracks, popped braces, failed glue joints, etc, etc.
With due care, and assuming we don't go commercial before we truly believe we're ready to do so, you would think there would be little cause for concern, however, I always think it's good policy to consider the worst-case scenario and be prepared to deal with it. I read on the OLF that some luthiers are prepared to bear the cost of a repair even if the owner is obviously at fault, weighing the cost they incur against the potential for bad press. Who'd be a luthier?
Others who have already gone down this path would of course be better qualified to offer an opinion. I hope they can chime in.