I think overthewing touches on an interesting point. He is referring to confidence, or the warm and fuzzy cosseted feeling passengers want to receive. Entirely different than suggesting significant ADDs are carried, or not even written up - if you see poorly paid, unmotivated staff, who clearly should not be in the job, anyone will draw those same conclusions about the oily bits on an aircraft, irrespective of the truth.
Whatever you may want to feel, having a 18 year old with no manners and being rude doesn't inspire any confidence, or the desire to return. Appearance, confidence and the experience means alot to the average punter.