Many years ago I was on a consulting assignment for a school district in the Chicago suburbs.
As I was the only person in the company assigned to this particular client, I had to rely on the customer contact to do final testing and approval of the modifications I made.
One one particularly critical fix, I completed the coding, did my unit testing, and ask the customer to do the final testing and sign off on it (assuming, of course, it was satisfactory).
Two days later I get a angry call from my boss who said he got an even angrier call from the customer. The fix I made had failed due to a condition that had not been considered ... and that the customers system were now down.
I had to meet my boss at the customers site so I could repair the problem ... thing was, I didn't even know it had been put into production. The customer had never given me the sign off form indicating that he approved the fix.
Turns out he hadn't bothered testing it at all ... he just put the program into production (I did have a pretty good track record). He had been doing this for months with my code. After the modification had been in production for a few days, he signed the approval form and gave it to me.
Of course now that a problem had been found, he was royally pissed ... and so was his boss. They were both demanding that I be fired.
Luckily my boss, after hearing the situation, figured out what was going on and told me that I wasn't at risk of loosing my job (although I was going to get a new assignment). He negotiated with the customer to have us fix the problem and they would have a new programmer assigned to the account.
The co-worker who got assigned to the account recounted the tales of my incompetence that the customer told her.
Let's see ... pot, kettle, black ... any questions?