Cars didn't use to come with turn signals. Before about 1939, an outstretched arm was good enough. Now, of course, signals are standard equipment.

Not that you'd know that if you spent any time driving throughout Washington. Many drivers eschew turn signals, apparently concerned about the wear and tear that flipping the lever would put on the tiny filament inside the signal's light bulb. Poor, precious filament.

But there's something even worse than not using a turn signal: using one.

That's what several readers pointed out after last week's column on various pet peeves of mine.

"True, many drivers do not signal turns," wrote Centreville's Stephen Vandivere. "The trouble is, those that do, don't. Don't actually always turn, that is. My wife was struck by a car because she believed the other driver's turn signal. I have been wavering between whether people should signal or whether the signals should be removed from all cars. My rule is don't believe a turn signal unless it is dangerous not to, which is a rare circumstance."

Joel L. Cohen of Silver Spring concurs. "One could be killed very easily trying to make a left-hand turn into traffic" on the assumption the car coming toward you is turning, he said. "I would rather a driver not signal at all than use the signals incorrectly."

Joel says the only way to survive on the road is to take note of the "body language" of other cars: "If a car has a signal on and appears to be slowing for a turn, odds are everything is fine," he said. "If they are signaling a turn but have not slowed down, odds are they are not going to turn, and all bets are off. In no case can one assume a turn signal is the 100 percent intent of the driver. To do so is living in a fool's paradise."

Doug Moore of Woodbridge said his mother was born in 1929 and began driving shortly after World War II, when gasoline rationing was eased.

"She is still going strong today and continues to drive herself and any passengers who care to come along," said Doug. "In all that time and mileage, she has been involved in only one at-fault accident. As I imagine you've already surmised, she pulled out in front a vehicle that had a turn signal flashing. Bang!"

It all gives one pause, doesn't it? Are we teetering on the edge of some sort of traffic free-for-all, where the agreed-upon rules of behavior no longer apply or can no longer be believed?

Untrustworthy turn signals might be just the start. It won't be too long before we all stop at green lights, not quite convinced that our fellow drivers are going to stop at red ones.

Dental as Anything

In that same column, I seethed over my irritation at having to address appointment-reminder postcards to myself at the dentist's office.

Carolyn O'Brien of Alexandria is a fellow traveler.

"I, too, was infuriated at being given cards to address each time I visited the dentist," she wrote. "So I address each one to 'Poor, Dear Carolyn,' 'Suffering Old Miss O'Brien,' 'Poor, Patient Patient,' etc. They always are used without further comment or endorsement by the dental office -- to the amusement of myself and perhaps my mailman, who has never commented, however."

A discreet mailman is a valuable commodity.

I've done the same thing, giving myself a droll nickname on what I've learned is called a "recall card."

Here's something else I do: Whenever I order something for myself online from Lands End, I always choose the "include personalized message" option. Then I type in some bit of doggerel so that when I open the package I can chuckle at the message and wonder if whoever packed my order found it amusing -- or peculiar. My last order of dress shirts included this spur-of-the-moment koan: "It is better to go clothed than naked, unless you are a dog."

(The first time I did this, My Lovely Wife opened the package and wondered why Lands End was sending us weird poetry.)

My dentist screed -- in which I bemoaned everything from the feel of the X-ray film to the taste of the tooth polish -- brought this reaction from Brookeville's Donna R. Blank: "You're a moron! Okay, rant over."

Donna, a registered dental hygienist who works with her dentist husband, Henry, in Silver Spring, rose to the defense of her profession. "We have you address your own dental recall card to be sure we catch any address changes," she explained. "While you are addressing your recall card, I am able to update your health history or perhaps set up particular implements for your procedure. This saves time and perhaps will alleviate the whining you do about the length of our appointment."

Donna said her patients appreciate the dental experience she provides.

"My husband and I work very hard to promote the health and well-being of our patients," she wrote. "Next time you want to complain about a profession, choose your own. There's plenty of material there for you."

Help a D.C. School

In case you missed last week's announcement: Duke Ellington School of the Arts is the District school we're helping out this year.

How? By designating it as the beneficiary of your grocery-store frequent-buyer card.

The school is already signed up with Giant (the school's number is 00074), Safeway (149191023), Harris Teeter (5912) and Target (39613).

It will soon be part of the program run by Food Lion, too.

My e-mail: kellyj@washpost.com.