I went through two set of front tires driving less than 2000 miles on both sets. First pair wore out the outside edges to the cords, second pair wore out the inside edges.
After the first set wore out prematurely, an alignment/tire shop mentioned nothing about finding worn part but sold me two new tires. After the new pair started to wear rapindly, a second alignment shop said the driver's lower ball joint was a "little loose" but only offered a re-alignment and did not replace any parts. When I noticed the second set of tires continued to wear rapidly, a third shop told me the driver's side lower ball joint was so loose it was about to self-destruct. The third shop replaced the worn parts (the first two shops failed to repair) and sold me the second pair of new front tires. So far, so good.