One time my parent's business was audited by the state tax board. They put my parents through hell and had a paid tax thief come out daily to their business to go over their books and records for a period of months. It cost the state his salary and whatnot and my parents had to spend months of their time providing documents and such. The state finally figured out a discrepancy of $100.
The upside is that I'm sure my dad put the tax thief through hell by constantly preaching about libertarianism and the Libertarian party for the entire time the tax thief was there. I'm sure he couldn't wait to get out of there ;).