HOW GENEROUS many businessmen are in their hospitality. Miss Manners has often wondered at their capacity to lavish time and expense accounts on people who are then likely to work against them, as a fifth column among their clients and associates.

These are the wives and sweethearts of businessmen, sometimes invited along to parties or restaurant meals of a professional nature. The host encourages this because he knows that an evening a couple spends at such a party will be counted by them as going out, rather than working late; or because he knows that he is not likely to entice his prey away from a dinner date, at any rate in a pleasant frame of mind.

But by the time a host has finished being what he considers charming to such a lady, the chances are he has developed an enemy. After some combination of being patronized and ignored, the lady will express an opinion where it will do the most harm. If the couple is in the habit of raking over the people they meet -- one of the great intimate pleasures -- she may only say, "That twit on my right asked me my name three times and still didn't get it right." A less outspoken lady will do more insidious damage by remarking vaguely, "Oh, I don't know, there was something I didn't quite trust about that man."

How does a well-meaning businessman achieve this result at his own expense, so to speak? By assuming that the lady does nothing of importance herself -- or challenging her to prove that she does. By refraining from boring her with business, turning away from her when that is discussed, and searching for topics he presumes to be more suitable when forced to converse with her.

Such rudeness cannot be classified as garden-variety anti-feminism. In fact, Miss Manners has noticed that taking a superior tone toward wives -- she has rarely heard of its happening to businesswomen's husbands -- is a common fault of men who profess to espouse equality, and is sometimes also practiced by professional women.

Gentlemen of the old school are less likely to offend, having been trained in politeness to ladies, whatever they really think of them. In spite of what these gentlemen's own daughters may confide afterwards about their porcine tendencies, they may select the correct approach automatically.

That is to treat the guests who are there through marriage or its equivalent the same as the guests who are there through their jobs. It is to assume that the lady takes an interest in the work being discussed or she would have found something else to do and let the gentlemen attend alone.

Everyone occasionally attends an event connected with the achievements of a friend or relative. The graceful way to do this -- whether it is a fiance's business lunch or a child's school assembly -- is to minimize one's own identity and exhibit supportive interest in the other person's. Miss Manners does not approve of the I'm-someone-too! approach to getting attention at such a function. When there is equality, both spouses know how and when to be the accompanyist.

But they retain the right to feel insulted when deprived of the dignity of this function by people who act as if they must be too insecure or uninformed to take an intelligent interest in the proceedings. MISS MANNERS RESPONDS

Q: Please list some tactful ways of removing a man's saliva from your face.

A: Please list some decent ways of acquiring a man's saliva on your face. If the gentleman sprayed you inadvertently to accompany enthusiastic discourse, you may step back two paces, bring out your handkerchief, and go through the motions of wiping your nose, while trailing the cloth along your face to pick up whatever needs mopping along the route. If, however, the substance was acquired as a result of enthusiasm of a more intimate nature, you may delicately retrieve it with a flick of your pink tongue. Miss Manners can't believe she said that. Please disregard that, and use the more delicate method of resting your cheek momentarily on his shoulder, until his jacket absorbs the mess.

Q: Please advise me on the proper way to address the name on a gift to be sent ahead of time to the home of the bride-to-be. Is it "Mr. and Mrs. Joe America" (name of groom-to-be) or Jane Doe? Need an answer soon.

A: The custom is to address all pre-wedding presents to the bride-to-be, and those sent after the marriage to the couple. Nowadays some people may take offense at anything. However, sending people checks goes a long way toward mitigating any offense.

Q: In a previous column, you replied to a question about wrapping place settings in a napkin and placing them on plates. I was always taught it was proper to place the place settings on the left and right sides of the plate. Can you please tell me who is your authority?

A. No, no, not the place setting, if that is what you mean by the flatware, and perhaps even the china and glasses. The instructions to which you refer concerned wrapping a roll in a napkin, an Edwardian custom that was bad enough, leading as it did to surprises in the lap. Wrapping up one's place plate, or whatever, would be an even bigger mistake.

Q. Some people whom I truthfully don't particularly like and have been avoiding, finally lured me to their home by inviting a couple whom I had always wanted to meet. Now that I know this couple socially, I would like to include them at my next dinner party. The people who introduced me to them frankly wouldn't fit in. I seem to recall that there was an old rule about not inviting new people unless you also invite the people through whom you met them, but I don't know why or whether this is still in effect.

A. Yes, it is. The purpose is to clothe the art of social climbing with some decency, so that the act of acquiring new friends is not directly linked with the related act of dropping old ones.

Q. My sister has recently given birth to her fourth daughter. It's no secret that they were trying for a boy, and yet I know it hurts her when people keep mentioning this fact when they come to visit the new baby. I mean, she's not going to send it back, so what's the point?

A. Indeed, but what was the point in her expressing her preferences beforehand? Unless there is a throne to be filled, the official position of prospective parents should always be that they don't care what sex the baby is (the phrase "so long as it's healthy" is an optional extra). However untrue this may be, there is nothing to be gained by stating a first choice. Refusing to do so may discourage rude post-natal evaluations on the part of others. It will also deprive the baby of a lifetime of attributing her every discontentment to the idea that "I was supposed to be a boy."

Q. Because of a religious preference our two daughters are being married at different churches on the same day. One wedding is at 3, and one is at 5. We are giving a joint wedding reception that evening. Both grooms are from out of town and the respective families and friends are acquainted.

We plan to send one invitation for both weddings. The printing would be on the inside folio. The left inside page would be for one couple, and the right inside page for the other couple (pages two and three).

Some people feel this would be in poor taste, as it obligate the recipients to give gifts to both couples, even though they might only know one couple. Others say, not so. On the other hand, if we use separate invitations, how will we handle the surprise of a second bride and groom at the reception? Also, how might we send the reception card with a separate invitation?

A. You are planning quite a day. You will soon realize, if you don't already, why there isn't a great body of precedent for holding two separate location weddings on the same day.

However, Miss Manners thinks it sounds like great fun for your guests, and would encourage you to include everyone for the entire marathon. (Miss Manners hopes people will have the sense to send presents only to the bridal couple they know, understanding that they are being included at the other wedding only because that is part of the festival.)

The double invitation you suggest, on facing pages, sounds sensible. In a one-location double wedding, both couples' names are given in one invitation, in order of bridal seniority (elder daughter first), but it would be impossible to sort out times and churches on yours.

You need only include a reception card with such an invitation. However, if you decide not to invite everyone to both ceremonies, make your chief invitation one to the joint wedding reception and enclose separate cards for the appropriate ceremonies.