Some people are secretly taking photos up women's skirts and down into bathroom stalls. Others are avoiding buying books and magazines by snapping free shots of desired pages.
"The problem with a new technology is that society has yet to come up with a common understanding about appropriate behavior," said Mizuko Ito, an expert on mobile phone culture at Keio University in Tokyo. "No matter what the technology, there'll always be people who don't mind their manners."
While camera phones have been broadly available for only a few months in the United States, more than 25 million of the devices are out on the streets of Japan, which leads the world in fancy mobile phones.
In nearby South Korea, where more than 3 million cell phones equipped with cameras are believed to be in circulation, Samsung Electronics is banning their use in its semiconductor and research facilities, hoping to stave off industrial espionage.
Samsung, a leading maker of cell phones, is taking a low-tech approach — requiring employees and visitors to stick tape over the handset's camera lens.
"Digital shoplifting" is another concern.
Japan's magazine publishers association is mailing out 34,000 posters to bookstores asking patrons not to use camera phone to shoot pages from periodicals in lieu of buying them.
Simply taking pictures of magazines on store shelves generally does not constitute copyright violation under Japanese law if it's only for individual consumption and not distributed to others.
But bookstores say it is devastating sales.
"Times are tough already. And this kind of problem has to come falling from the sky," says Makoto Niikura, owner of the Yakumodo book store in Tokyo, which has put up a poster that says: "Magazine lovers watch their manners."
Minako Yamashita, a 32-year-old housewife who uses her cell phone to take pictures of her children, said she has witnessed people sneaking photos in bookstores and acknowledged a temptation to do it herself.
"I can understand," she said. "But I'd never do it."
A camera phone starts from virtually free for those rendering blurry photos to $300 models that offer digital-camera-quality images, albeit at tiny sizes.
It's still impossible to read an entire magazine page in a picture shot from a phone, even if the image is relayed to a personal computer. But photographing a restaurant address, information about job openings, a recipe or pop star's photo are well within the technology's range.
No government in Asia has yet tried to regulate camera phones. And South Korean manufacturers have already written the government opposing any possible regulation as a blow to sales, according to LG Electronics, a member of the industry group that wrote the letter.
Most people use the camera-phones for harmless things like jazzing up e-mail with snapshots. But perverse uses are cropping up.
Around Asia, fears are rising about photos being surreptitiously taken in swimming pools and locker rooms. Cell phones have already been declared off-limits by Japanese public bath houses.
Japanese police say they have apprehended people using camera phones to take photos up the skirts of unsuspecting women in crowded trains and stores. One culprit was fined $4,200.
In China, a teenager was raped by a man who photographed her nude with a camera-phone and threatened to disseminate the pictures, police said. One woman was sued for allegedly taking camera-phone pictures of another woman while she was in the bathroom and transmitting them to acquaintances.
Japan's camera phones are designed to set off an electronic ring when the shutter is pressed, warning everyone nearby that a photograph is being taken. But the alarm can be muffled by placing a hand or piece of cloth over the speakers, police say.
Then again, camera phones can enhance the safety of people in trouble.In Yokohama, Japan, an 18-year-old female store clerk used her camera phone to take a photo of a 38-year-old man who was fondling her on a commuter train. She called police during the train ride and presented her phone shots as evidence. The man was arrested at the next stop.
Daisuke Okabe, professor of education and human sciences at Yokohama National University, says rules about mobile phones ideally should be created by the users themselves, rather than forced upon them.
"Mobile technology can change social behavior, and social behavior leads to new mobile technology," he said. "It's a two-way street."