LONG BEACH, Calif. -- The grungy hotel room was reeking of smoke. The bathtub was rusty. The bedspread and furnishings were dingy relics.

But I couldn't leave.

I'd already paid $155 in an online travel auction for the Queen Mary Hotel room. I'd taken a risk. And lost.

Online travel auctions promise fabulous bargains on vacations, hotels and airfare to glamorous places, playing on travelers' desires to get a steal of a deal. Sometimes they work out wonderfully. Sometimes they don't.

''Since the beginning of man, people have always wanted more for less,'' says Greg Donewar, manager of the federal Internet Crime Complaint Center in Fairmont, W. Va.

``If it sounds too good to be true, beware.''

Ah, the old caveat emptor.

Travel auction sites come in two flavors -- nonprofit and for-profit. Some sites charge buyers commission. Some are actually travel agencies or consolidators. Others, like eBay's travel section, simply provide online auction space. Some sell last-minute unsold or even distressed products, while others specialize in high-end trips. A few are altruistic, donating your purchase price to charity.

Your biggest risk in a travel auction is failing to read the fine print -- blackout dates, commissions, fees, surcharges, taxes or other catches that can boost the price or lower the value of your winning bid.

Every year, complaints about online auctions top the list of reports to the Internet Crime Complaint Center, which is run by FBI and the federal White Collar Crime Task Force.

One good piece of news? Complaints about auction fraud are slowly dropping, Donewar says. That indicates that sites are stricter and consumers are smarter.

At least, most consumers are.

In my case, I registered on www.skyauction.com, then looked for an interesting California hotel, settling on a room at the historic, retired Queen Mary cruise ship. I bid $12 to start for a room, then went up to $14, $30, $45 and $91. I got a message the next day telling me I'd won. Then I paid $20 to upgrade from an inside stateroom (no window) to an outside stateroom (porthole window), the $20 commission to SkyAuction and $24 in taxes. I requested lodging dates. My credit card was charged. The reservation was nonrefundable and nonchangeable.

(I never checked the hotel's own rates. If I had, I would have found that its own website offered better rooms for as low as $99 a night plus tax.)

I'm not picky, but when I got to room A-028 at the Queen Mary, I almost cried. It was appalling. I returned to the front desk and requested something less smoky and dingy. The clerk gave me a slightly larger, nonsmoking room. It, like the rest of the 350-room hotel ship, was direly in need of renovation. I couldn't understand why the hotel was in such bad shape.

I found out why later. The Queen Mary has been in bankruptcy proceedings for two years. A planned sale of the lease has been held up by a dispute over adjacent land. Its operators are not exactly going to be springing for new stuff on the ship. The hotel gets a low grade of D from the Better Business Bureau because of complaints.

SkyAuction's president Michael Hering points out that many travel sites like Expedia and Orbitz sell rooms at the Queen Mary, too. If buyers don't do their homework or read the fine print, they have nothing to complain about, he says. (The Queen Mary is not currently listed on SkyAuction.)

SkyAuction is the only travel auction site with an unsatisfactory rating by the Better Business Bureau, based on a pattern of complaints.