A local consumer group spent all summer monitoring TV commercials and discovered what the average viewer knew all along: commercials are short on factual information and long on advertising puffery.

The consumer group didn't mention another complaint: Commercials are repeated so often that even those that are irritating enough to be noticed for a while soon become so boring they no longer register on the viewer's brain.

Mrs. A. McCutchen of Riverdale thinks the Topol radio commercial is the worst of the lot. This is the commercial that begins with a smoker wondering what set off his smoke alarm. A friend says, in a disapproving tone, that the smoker's cigarette set it off.

He asks the smoker to blow smoke through a white handerchief. The puff of smoke leaves an ugly yellow stain, whereupon the friend says something on the order of, "You see that, dummy? What you need is Topol, the smoker's tooth polish."

So the smoker rushes out to buy Topol, a 3-ounce tube of which sells for about $4 ($1.33 per ounce, compared to a price of between 12 and 17 cents per ounce for most popular brands).

It seems to me that such a commercial would evoke for the average listener a mental image of lung pictures he has seen, perhaps in his doctor's office: the nonsmoker's healthy pink lungs and the smoker's lungs that have been blackened to the color of charred wood. Surely it would occur to an intelligent person that if one puff of smoke stains a handerchief, scores of puffs every day can be fatal to human tissue.

But the smoker in the commercial doesn't have brains enough to associate the stain on the handerchief with his lungs. He's utterly delighted with the whiteness of his teeth since he began using Topol.

Now all he had to do is find a toothbrush with an extra-long handle and figure out a way to scrub his lungs with Topol. Madison Avenue, you're just too much. THESE MODERN TIMES

Sunday's financial section led off with a story that really made me angry. It was written by Nancy L. Ross and told us about banks that do not permit their customers to draw against deposited checks for weeks -- 20 days or more.Banks claim they must do this to protect themselves until they are sure the deposited check has "cleared" (been honored by the bank upon which it was drawn).

This is hogwash. The Federal Reserve will tell you that most local checks clear during the business day that follows the date of deposit. Most out-of-town checks clear in three or four days.

The speed of mail service has little to do with clearing checks.

There is such a heavy volume of check traffic among all the major cities in this country that banks seldom use the mails. They use either courier services or "consolidated shipments."

A check on a Seattle bank deposited here on a Monday is usually processed on Monday night, delivered in Seattle on Tuesday, and processed in Seattle by Wednesday. If the Seattle bank refuses to honor the check, it must -- by law -- return it by the following midnight -- which in this instance would mean by midnight Thursday.

Yet one who has been a customer of a Washington bank for 25 years can deposit a dividend check from IBM, or a paycheck from The Washington Post, and be told that he can't use his money for 10 days, two weeks, three weeks or whatever other arbitrary period of time pops into the banker's head. The bank, meanwhile, lends out the customer's money at the absurd interest rates that are now in vogue.

I would think that an industry that wants us to adapt to the electronic transfer of funds would be embarrassed to engage in such practices. GOOD NEWS, FOR A CHANGE

In 1923, the first year we kept traffic accident records in Washington, 133 people died in auto crashes. Within a few decades, the annual toll was more than 200. That's when we embarked on safety campaigns, and the death list began to get smaller.

In 1979, we reduced auto deaths to 50, a record low. So far this year, we're doing even better. As these lines were written, 36 people had died in traffic here, compared to 40 on the same date last year.

So be alert and obey the law. It does make a difference.