(MONEY Magazine) – Too often, travelers seem to leave their street smarts at home. ''There aren't any new scams,'' says Bob Louden, a 21-year veteran of New York City's police force who trains cops at John Jay College of Criminal Justice. ''There are only new victims.'' ''Don't let down your guard just because you're on vacation,'' cautions Ann Waigand of the Educated Traveler newsletter ($65 a year; 703-471-1063). She * and others warn in particular about robbers who stage planned distractions in crowded places, such as airports or theaters. Therefore, stay alert for engineered mishaps like these: -- Some stranger spills ketchup all over your suit and, as you or he frantically wipes it off, he lifts your wallet and maybe your luggage. -- A real nice guy offers to snap a picture of you and your family on vacation and, as you back up, he disappears with your camera. -- A pedestrian jumps in front of your car and falls down. When you get out to help the poor guy, he runs around, slips behind the wheel and drives off. Hotels are not necessarily safer ground. ''The oldest scam in the book,'' points out Roland Boisvert, security director at Royal Sonesta Hotel in Cambridge, Mass., ''is hanging out at the front desk, overhearing the guest's name and room number and then using it to gain entry later.'' Keep these hotel safety procedures in mind: -- Make sure the clerk hands over your key without loudly announcing your room number. If he does, demand another room, whisper-quiet. -- Check all locks thoroughly as soon as you enter any room. Request another if you're dissatisfied. By the way, those new coded electronic cards are safer than ordinary key locks. -- Always call the front desk for verification when a caller asks you to leave the room. It could be a crook's ruse. -- Do keep valuables in hotel safes, but remember: the hotel's liability varies with state law and can be as low as $50. -- If a clerk makes an imprint of your credit card when you check in but you pay in cash, make certain the imprint is destroyed. An employee could pocket your cash and put the bill on your card. Since even the most careful traveler can become a victim, always leave the numbers of your passport, credit cards and traveler's checks at home just in case you need to replace them in a hurry. Most victims are too embarrassed, too cynical or simply too busy to report cash or credit-card thefts to the police. They just replace what they can and continue traveling. Even so, in 1990, reports of luggage and pickpocket thefts at New York City's Kennedy Airport totaled 1,060. And last year in Orange County, Calif., home to Disneyland and Knott's Berry Farm, almost 25% of the emergency cases that were handled by the Traveler's Aid centers were crime- related. So be careful.