I speak from experience here. My wife and I own a condominium in Naples, Fla. One of our neighbors is as bad as neighbors come. In Florida real estate parlance, he is a "condo commando" — a busybody who questions other residents on what they are doing and then routinely complains to the condo's board about them.

Bad neighbors abound everywhere, but they seem particularly bothersome when they are in places where you go to relax. Shouldn't everyone just be grateful to be sitting in the sun or at fireside near the ski slopes?

The dynamics of second homeownership often conspire against this, said Milton F. Pedraza, chief executive of the Luxury Institute, an organization that does research on wealthy consumers. "People become slaves to their homes. They buy into the headlines and that makes them pretty miserable with their vacation homes."

Mr. Pedraza said one common cause of second-home misery was that owners failed to factor in how much time and money were needed to maintain a place from hundreds, if not thousands, of miles away.

My colleague Ron Lieber recently wrote about answering the tough financial questions that children ask their parents. That made me think that adults buying second homes should ask equally tough questions — of themselves. Why, after all, do you want a second home? What are you going to use it for? Do you have any idea how much it is really going to cost?

While many parts of the country are still struggling with falling home prices, a survey from the National Association of Realtors said sales of second homes were up 7.9 percent last year, compared with a 7.1 percent increase for primary residences. And this is the time of year when people begin to look for the winter rentals that often turn into second homes.

Before you jump in, here's a look at what you should know before buying a second home.

IT'S NOT AN INVESTMENT If the recession taught people anything, it is that the value of a home can go down. Vacation properties are certainly not immune.

Beyond the ups and downs of the real estate market, Mr. Pedraza said most buyers underestimated the maintenance costs of a second home.

"Think of the 20 to 25 suppliers who come to your house for air-conditioning, heating, landscaping, the pool man, the plumber — now you've got to procure those same suppliers for another property," he said. "If you have the money and it doesn't mean anything to you from an investment point of view and you can hire the staff, then fine."

Deb Howard, a realtor in Lake Tahoe and chairwoman of the National Association of Realtors' resort and second home committee, said many people looked at the properties as a place for the family to gather and as something to leave to the children. But they still need to consider the carrying costs of the property.

Ms. Howard says her first question to buyers is always what kind of lifestyle they expect to have. But her second is whether they need to rent the home to cover the costs. "Sometimes it's not the right decision," Ms. Howard said. "You're not going to use it enough. Or it's not going to meet your financial goals."

IT'S LESS RELAXING What persuades people to buy a second home is usually a vacation. A second home, they think, will keep the party going with the added benefit of having a place of their own.

"They only see the benefits — sitting by the pool, having a piña colada, driving into the driveway and leaving the Rolls Royce there," Mr. Pedraza said. "They never figure the gate is going to be broken and they will need an electrician." (You will also be making your own piña coladas and cleaning out the blender.)

Enthusiasm for a place can also lead to a hasty purchase. Barry Peele, of Sotheby's International Realty in Beverly Hills, said a client recently bought a waterfront home in Miami only to find out after the closing that the dock would not accommodate his yacht. Suddenly, the convenience of walking out to his boat — the original attraction — was gone.

And then there is the pressure to use the place. "People have high expectations of their usage," said Brian Sharples, chief executive of HomeAway, which runs several vacation rental Web sites. "The industry average is 30 days of use per year."