I was once somewhat insulted:

I started a new consulting job to complete a program that was “almost finished”, because the original programmer had quit. I was soon able to show that the program was far from finished (I completed it in three months). On my third day of work I found that two parts of the program had been designed in conflict, so that a third part would be impossible to complete. I thought it best to ask the original programmer how to resolve this issue. I got his phone number, called and described the issue to him.
“That’s amazing,” he said, “I would have expected you to work on my program for a month before you understood that problem.”
You might argue that he actually paid me a compliment. Didn’t feel like it though.