``Don't look for trouble.'' That's what my mother always told me. Or maybe she said it once, but let her try to get the Herald to run a correction.

In any case, the advice sunk in. I don't try on bathing suits in stores with three-way mirrors. I don't take those quizzes aimed at proving how uninformed Americans are. (Q: Paris is the capital of . . . ?) I don't wait and see if I'll be carded at Trader Joe's, where the policy is to check IDs for shoppers who appear younger than 40. I simply hand over my license with my credit card, and don't watch to see if the clerk looks at it.

The latest no-no are those full-body CT scans for healthy people, which, you may have heard, are becoming available at bargain prices to the masses, or as doctors call them, the ``worried well.''

The just-checking scans were once an executive perk (albeit a lousy one), but sadly, like Botox injections and cell phones, they've trickled down.

So now for a few hundred dollars you can have a region of your body scanned for tiny tumors, weak spots on blood vessels and early signs of heart disease. One firm, which has mobile units that prowl around the nation's highways, offers a three-fer: three scans for $567.

Don't get me wrong. I'm not against technology. I'd happily submit myself to one of those computer programs that shows you how you'd look with Kelly Rippa's hair, or as a redhead, or with bangs.

True, the hair program is not without its own flaws - you could get a drastic cut only to have Kelly change her style a few days later - but the CT scans are even more dangerous. They can reveal abnormalities that pose no real health threat, thereby prompting a person to get additional tests, which are not only expensive but risky, too.

When I read about the scans the other day I recalled my own brush with prophylactic scanning a few years ago. I was enjoying a routine dental cleaning when the hygienist, a rogue employee who later left ``under circumstances'' pulled out an implement and grinned.

``There's a little camera in here,'' she said, sticking the tool in my mouth and running it over my teeth, even as I bit down to stop her.

``Look at the monitor,'' she said, as incisors and molars and canines loomed on screen, larger than life. ``I can tell you which tooth will need a root canal years before you'll feel anything.''

I've been less scared in Stephen King movies. ``No!'' I shrieked, covering my eyes with my hands and humming so I didn't hear any narration she might have been giving.

As you can imagine, I couldn't get out of there fast enough. I pulled off my bib - then rinsed, handed over my co-pay and made an appointment for six months hence - and then hustled out into the daylight, shaken.

``That's why I'd never do one of those body tests,'' I told a friend. ``There are some things you don't want to know.''

She wouldn't do one either, she said, but for a different reason. She's a hypochondriac, and unless the tests were done daily, they'd provide no solace.

``How would I know that the bad cells didn't start growing the moment after they finished the scan?'' she asked. ``I'd have to spend every waking hour getting scanned.''

Then, of course, she'd have to worry about the long-term risks of exposure to X-rays.

``With any luck,'' she added, ``I'd die in an accident, and it would have all been for nothing.''