Check out this post over on sister-site irstaxreliefattorney.net: "the Four Most Dangerous types of Revenue Officers."
Here's my fav:
3. The guy/girl you jerked around.
Sometimes he's willing to let bygones be bygones. But sometimes he or she will take it personally. And sometimes they will have the backing of their group manager And their group manager's territory manager
Never anger a Revenue Officer who would wear those shoes.