I don't think you do, respectfully speaking. From a IRS Code perspective that is. Plenty of returns show lots of income yet at the bottom of the return show zero or negative "total income" or "adjusted gross income".

"Gross income"? Term is nowhere on a 1040. I think the author left out the "adjusted" qualifier.

http://www.irs.gov/pub/irs-soi/14inwinbulincomeprlim12.pdf

Consider this as well. What the IRS calls audits these days aren't what your father's audit was. The IRS IS severely understaffed. Even practitoners have difficulty getting problems resolved. Pity the poor public.
A lot of screening & scoring is done on efiled returns. Most audit notices are generated in this manner. Automatically. Correspondence audits. Send in the documentation. Since more & more returns show up at the IRS as "self-prepared" from home computers, it doesn't surprise me in the least that audits of John & Jane Does have higher audit counts..in sheer numbers. Most of them are probably self inflicted wounds to boot!
CPA's & tax attorneys are hired to prepare bullet proof returns, not to get cleints audited.