The wealthy often employ an army of household assistants, from cooks and drivers to housekeepers and pool cleaners, to maintain a lavish lifestyle. But sometimes "the help" can turn astronomically expensive, especially if their employer makes a misstep.

"If a Wall Street guy comes home after having a few drinks and says something sexual to the nanny, not even blatant but just innocently, and she blows it off, she might not blow it off later," says Clement.

"Nanny coverage," also known by the unwieldy name Employment Practices Liability Coverage, or EPLI for short, is typically a rider on an umbrella policy that protects the wealthy against claims by personal employees for discrimination, wrongful termination and sexual harassment.

"Hiring is the key," Clement says. "If something is going to go wrong, it's going to be someone connected with your personal staff. They could plant hidden cameras; they could be connected to an extortion ring to kidnap the kids. As soon as I know that a client has household staff, I automatically include that coverage."