A hot job offer dangles before you. How do you know if it’s right? Sometimes you feel it in your gut. And sometimes you get a big, bloody warning sign. Like Sallie Krawcheck did before she opted to join Bank of America .

Krawcheck, the former Citigroup star who joined BofA in August to head its Global Wealth and Investment Management unit, told a story last evening in an on-stage conversation with my Fortune colleague Carol Loomis at Manhattan’s Museum of American Finance. While she ducked all questions about who might replace departing BofA CEO Ken Lewis (she’s rumored to be in the running, but she’s a longshot), Krawcheck had the audience rolling as she talked about another job that she almost took–until things went awry.

This other job, explained Krawcheck, 44, was “a leadership opportunity at a troubled financial-services company.” The initial meeting with the prospective employer required a flight out of New York. “For the first time in my life, I overslept and almost missed the plane.” No time for a shower, she threw on her clothes. “I think my pajamas were on underneath,” she said.

She thought to herself: “This doesn’t feel very good.”

Krawcheck made it to the meeting, however, and it went well. The second meeting took place, conveniently, in Manhattan. This was a beautiful spring day. Wearing a new suit and new shoes, she recalled, “I couldn’t have been feeling more pleased with myself.”

That is, until Krawcheck, while walking down Madison Avenue to her meeting, caught the heel of her new shoe in a crack in the sidewalk.

“I went flying down onto a grate,” she said. “I stood up, spit out a tooth. Blood was everywhere.”

Still, she was determined: “I can make the meeting. I can make the meeting!”

“I did not make the meeting. Nor did I eat solid food for the next six weeks.”

“I ended up with six stitches, one broken tooth, a hairline jaw fracture, a dislocated jaw and whiplash.”

Yes, the meeting happened, eventually. In fact, the fit between Krawcheck and this financial-services company seemed ideal. She accepted the job offer.

And then, when she went to sign the employment agreement, “I promptly threw up. And I thought, I don’t think this is right for me.”

And that’s how Sallie Krawcheck, No. 30 on Fortune‘s Most Powerful Women in Business list, passed up one big opportunity before accepting another at BofA.