A friend approached a garage owner for a job. "I'm the best mechanic you will ever employ. I can tell the make and year of any vehicle and tell you what's wrong with it, just by listening to it." So the chap blindfolded him, and ran the engines of the cars awaiting repair.
"1998 Mondeo 1.8, tappets need adjusting."
"2002 Daewoo 1.6, timing is 2 degrees too advanced and choke is part on."
"2001 Mercedes 2.2, perfectly OK, must be in for an oil change."
And so it went on and every diagnosis checked with the job sheets. So the boss led him by the toilet. He flushed it and emptied a bucket of nuts and bolts over a steel workbench.
