What did you do on your summer vacation?

And aren't you glad Miss Manners asked?

The suspicious reader may notice what a remarkably short time it took Miss Manners to get from asking about you to talking about herself. That is the problem she wishes to illustrate.

Here you are, back from a holiday on which you loyally kept your dear friends constantly in mind. "That will wow them" (more likely " 'em," which Miss Manners does not allow herself) you mused, as you fashioned a running commentary of what you saw and did. "Wait till they hear about that back home."

They still have not heard, although you have been home for a while. Nobody will listen. No sooner do you begin than you are stopped by one or more of the following responses:

"Yes, well, let me tell you what's been happening around here."

"That reminds me of what happened to me once."

"Did you eat at that little restaurant about six blocks from the town hall, with the hidden entrance to the side of the park? No? You don't know what you've missed."

"How much did you pay? Really? You should have talked to me before you went. I'm afraid you've been had."

"You should have been there before it was spoiled by the tourists. Then it was really worth going there."

At this point the returning vacationer, if easily bruised, might worry about his or her ability to plan a holiday, let alone to get two sentences out without boring people senseless.

Allow Miss Manners to say reassuringly that neither of those possible defects is the trouble.

There is no place to vacation where no traveler has set foot before, except possibly one's own back yard, and probably not even that. The definition of a wonderful little place to eat is a place nobody else knows about; if you had been there, you would have been told it was not worth going to anymore. And there aren't too many places where the prices just keep going down. If you hear of one, Miss Manners would appreciate your letting her know.

We know it wasn't boredom that estranged the listeners, because to be boring you have to be allowed to say something.

It is true that the returned vacationer suffers from the reputation of others in the same position -- legendary figures who actually got their stories out. According to folk memory, these people did such a thorough job of numbing all their friends, with the help of postal cards, souvenirs, and all manifestations of which the photographic process is capable, that they ruined in perpetuity the reputation of anyone who has ever utilized time off from work for more than mowing the lawn. These figures from the past are also said to have done their job with malicious intent. Far from wanting to share their joys and discoveries, they lived to make others feel discontented with their own lot for not having been along. Braggarts and bores may not be interchangeable, but the combination is unbeatable.

Nevertheless, Miss Manners can hardly imagine that the sins of previous generations of merrymakers are what make otherwise well-disposed friends wary of those who have been away.

She suspects that the problem, rather, is that the art, or grace, of listening to long, cheerful narratives by friends or relations seems to have been lost. Before anyone blames that on the national attention span, she wishes to point out that drawn-out tragedy is politely presumed to have conversational right of way.

It may well be that the story of your bleak love life is less gripping than the story of your adventures at the beach. A report about your feelings of worthlessness is likely to be devoid of incident, while a report about your dream trip may be sparkling with it. Yet kindly people who feel obliged to listen to the former, even repeatedly and at odd hours, have little patience for the latter.

Well, vacations, too, need to be told. An otherwise normal person cannot be expected to disappear for a week or a month, reappear in accustomed surroundings, and not have something to tell.

The mannerly person will stand still long enough to listen. It may even give him or her an idea about where to go at the next opportunity. The first entry in the vacation book should be who has to listen to it all at home.

Q. I went to the post office to get stamps and other miscellaneous items. The polite young lady who served me made no effort to avert her head when she suddenly let forth an enormous sneeze, all over my purchase and her hands.

Rather than make an unkind comment, I timidly let the matter go and grudgingly collected my change and items, but I wonder what you would have done under the circumstances -- if anything. After all, she could have turned her head away when she felt the sneeze coming on, and not shared any germs.

A. Miss Manners would have confined herself to uttering a mild "Bless you," perhaps accompanied by the polite request, "I wonder if you might give me some dry stamps instead."

Q. Is it improper to change from a bridesmaid's dress into a more becoming dress after the wedding ceremony?

A. How long after the ceremony? A bridesmaid is on duty through the reception, but when the wedding trip begins, she may go home and put on whatever she wants.

Miss Manners is sorry to hear of anyone's being forced into a dress she dislikes. She keeps telling brides to consult their bridesmaids on the highly personal subject of what they are to wear, and pointing out that uniformity, as opposed to harmony, is not an absolute requirement.

But if that battle is lost, changing for the reception merely informs everyone present that the bride has rotten taste. True or not, it is not one of the bridesmaid's duties to point that out.