But their victims share more similarities than differences.

Most are solo travelers, passing through crowded airports, hotels and car rental agencies at peak travel times. And nearly all are concentrating on their destinations, not on their surroundings or belongings.

"A lot of vacationers don't even realize they've been ripped off," Coffey says. "They're rushing to catch a plane to Hawaii, and they're already dreaming of that sandy beach."

Even frequent fliers aren't immune.

"We take it for granted that a '1K, aluminum-card' traveler must be pretty savvy," adds Coffey, who founded the Los Angeles Police Department's airport crimes division and now lectures on-the-road executives as owner of Corporate Travel Safety in Canoga Park, Calif.

"But they're loaded down like a pachyderm . . . they've got a sales quota to meet, and the last thing they're thinking about is that briefcase beside them."

Statistics on travel-related crimes are hard to come by, in part because thefts aren't reported by specific location and because many victims don't take the time to fill out a police report, Coffey says.

But while assaults are rare, "anytime you see a rise in travel, you see a rise in crime . . . there may not be that many criminals, but if you don't know how they operate, you become a mark," he adds.

With the busy summer travel season about to kick off, here's a rundown of common rip-off schemes and Coffey's advice on how to avoid them:

Shuttle bus shuffles. On many hotel and car rental shuttles, passenger luggage is stored behind the driver's seat or in a separate compartment at the rear. As a result, many passengers can't spot a thief who boards at one stop and gets off at the next - with the victim's suitcase in hand. Advice: Keep belongings in sight whenever possible, watch as the driver distributes bags, and mark look-alike luggage with brightly colored yarn or tape.

Curbside commotions. Don't rely on a skycap's assurances that your bags will make it to their intended destination, Coffey says. A well-dressed con artist can nab a bag from a waiting cart while the skycap is helping another customer. Advice: "I don't tip the handler until I see my bag make it onto the conveyer belt that goes into the terminal," he says.

Airline club crooks. At some members-only airline clubs, travelers can buzz in and stash their carry-ons in a storage area before showing their membership cards at the front desk. That's good news for would-be bandits, bad news for travelers who let down their guards in what "they assume is a protected environment," Coffey says. Advice: Never leave bags unattended, even in an airport club.

Security snafus. Some travelers are ripped off by thieves who work in pairs, diverting passengers' attention from their briefcases or laptops by purposely activating the alarm at security checkpoints. But by forgetting to remove keys and metal jewelry before they pass through the checkpoint, many passengers are "their own worst distraction," Coffey warns. Advice: Wait for the person in front of you to clear security before placing belongings on the conveyor belt.

Baggage claim bandits. Only a few major airports maintain a security checkpoint where bags are matched to claim tickets, and "there's big money to be made in stolen luggage . . . it's easy, it's quick and there's a very small chance of being caught," Coffey says. Advice: Don't dawdle on your way to the baggage claim area. Be alert to crooks who read uncovered luggage tags and call your name as though they know you; the resulting confusion allows an accomplice to steal your bags.

Hotel room hoists. "Everybody has this image of a guy in a black stocking cap, but the best crooks are also the best actors . . . they look and act just like their victims," Coffey says. Consequently, thieves who enter a hotel room during turndown service are rarely asked by maids to produce a key or identification. Advice: Store valuables in a hotel safe.