These mentions of audits are another reason it's good to use a pro for your taxes. If you're pushing your luck with a deduction, he'll know and recommend against it, or recommend how best to present it. If you get audited and used a pro, you are much more likely (in my opinion and from what I've heard) to have a happy outcome, since the pro can go with you and speaks their lingo. They can quote regs, etc. and present the audit guy with your side of things far better than you can. Believe it or not, in spite of the enormous size and detail of the tax code, some things are still open to interpretation to a larger degree than you'd believe.
An example: I totally screwed up and forgot to file an important form once, and my guy said "no problem, just file this and say this, then they'll let you file what you forgot with no problem, no fine, no nothing." And he was right, and I didn't lie or stretch the truth even. If I had just sent it in late, I would've been hit with a monthly fine for each month it was late. Hell, he didn't even bill me for the question and it saved me like $600 or something.
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DISCLAIMER: I'm not an attorney, CPA, tax guy, etc., and can barely even find my keys in the morning, so this is just FYI and I don't make any claim, warranty, guarantee that it is accurate. Always consult a professional. That's what they're there for, and the good ones are worth it.