HE MOST generous hosts Miss Manners knows of are careful to ensure that their guests receive nothing that is not of the highest quality and exactly to their taste, refuse to allow any reciprocation, and will not intrude on their privacy even to the extent of sharing with them in the bounty.

They entertain constantly, and, not content with dispensing food, drink and little presents, always try to slip a bit of cash unobtrusively into their guests' pockets.

These hosts are corporations. Miss Manners cannot bear it when corporations anthropomorphize themselves for the purpose of attributing desirable human qualities such as friendliness to their businesses, but she must do it herself in order to demonstrate how rude it is to impose on such hosts.

The illegal aspects of expense account life are not really in Miss Manners' domain. She would like to state haughtily that no person of gentle manners would ever dream of manipulating expense accounts to his personal benefit, but the evidence is against her.

However, there are legal methods, in quite common practice, of using expense accounts in ways that nevertheless violate the laws of etiquette. About those, she can be as haughty as she likes.

The widespread belief that nobody pays for expense account living, that the business world is simply bountiful in the way that nature is supposed to be, has affected the behavior not only of those who preside over the expense accounts, but the recipients of their invitations.

Miss Manners has nothing against the expense account meal, which has several clear business purposes:

To put a person on his social manners, which are more modest and agreeable and yielding than business manners, in order to secure a business advantage.

To create an obligation that must be reciprocated in services, rather than a return engagement.

To indicate that oneself and one's business are so prosperous that a luxurious standard of living is taken for granted by both.

To befuddle someone by food, drink or flattering conversation, so as to blunt his business sense.

You will notice that Miss Manners has not included on this list the exchange of valuable information and the shaping of business deals, but she does not object to those who wish to believe that that is what is done.

What must not be done is to sneer at the gullibility of the absent host, and recommend that he be fleeced.

This means that the keeper of the expense account does not extend normal hospitality by such remarks as, "Oh, come on, why not, I'm putting in for it," and that the recipient does not inquire, with the smugness of one who shows consideration and delicacy, "You're not paying for this yourself, are you?" before ordering.

Proper restaurant behavior, in case anyone has confused it with the rules of juvenile shoplifting partnerships, is for the host to mention a reasonably generous range of possibilities, but for the recipient to refrain from ordering courses or specialties without the insistence or example of the host. The worthy adage, "A lady always orders from the middle of the menu" applies to anyone not playing host. And ladies and gentlemen, in both their business and their social lives, always pretend that the company, and not the free groceries, are the attraction when they dine out, even when the groceries are provided by the company's company. MISS MANNERS RESPONDS

Q. My fiance' is in the nasty habit of saying "Thank you" after we have physically expressed our love (I'm trying to be dainty here). This seems somehow cold and mercenary to me. He is otherwise a perfect gentleman, but this misuse (?) of "Thank you" makes me cringe.

Although "Thank you" is all too underused these days, I wonder if this is a correct usage. If so, should my response be "You're welcome," or "Thank YOU!"?

Please, Miss Manners, please help me. I feel as though I've just handed him his dry cleaning, rather than demonstrated my undying love.

A. "You're welcome" is certainly one correct answer to "Thank you," and "Thank YOU" is all right, too. So is, "Oh, it was nothing, really," although Miss Manners does not particularly recommend that in this instance.

She is somewhat disturbed by your mentioning, in your case against the appropriateness of your fiance''s politeness, that you find it mercenary. Are you suggesting that he is thanking you for giving him free what he might otherwise have to pay for? Surely not. Cannot you assume, as Miss Manners certainly does, that his statement is a brief version of "Thank you for enriching my life and entrusting to me the great bounty of your love"?

If not, the fact that what ought to be a tender moment is one that you associate with dry cleaning, to put it equally daintily, is, although not an etiquette problem, a problem that Miss Manners strongly suggests you resolve between the two of you before proceeding any further.

Q. During the preparations for my wedding, a dispute arose with two family members. I refuse to argue, so will you please address the following issue:

I chose a maid-of-honor and two bridesmaids for my wedding party. I planned to have all of the attendants wear the same color gown to complete my intended theme. The maid of honor and her mother threw a tantrum, insisting that she wear a different color than the others. Regretfully, I gave in rather than have a huge argument. They also began to contest the choice of gowns.

I maintain that it is the bride who has the right to choose both the color and the gown, after the attendants agree upon a price range. Attendants may give input, but the final decision is the bride's. They still think that I am crazy, but I feel that they are gauche. Who is correct?

A. Whoever gave The Bride the notion that a wedding is her wedding, to be ordered just exactly as she has always dreamed, did the future of family life a terrible disservice.

Actually, weddings belong to practically everybody involved, the usual exception being the bridegroom. There is the bride's parents' wedding, the flower girl's wedding, each guest's wedding, and so on. The bride who tries to jam all these people into her picture is in for big trouble, as you and most brides have discovered.

There you are, thinking about your "intended theme," trying to deal with people who are thinking about all that money and time going into a dress none of them is crazy about, for an assortment of different reasons. The color is wrong for one person, the style for another, another has no use in her life for that kind of dress, and all of them know that the same dress will be owned by an assortment of people they are likely to run into again.

You will only be able to move their hearts so far with your babblings about them all looking like a garden of fuchsias, or whatever.

A little tact and compromise is called for here, the exercise of which will not be a bad preparation for married life. If you get all the attendants together and let them air their objections and preferences, the chances are these will cancel one another out, and when the one who hates puffy sleeves has been snapping at the one who says that yellow makes her skin look sallow and the one who is chiming in that chiffon doesn't fit into her lifestyle, they will be only too glad to turn things over to you when you say plaintively, while apparently having conceded that their opinions are your commands, "But I thought each of you would look so pretty in this--it's the kind of dress I always dreamed about."

Q. My sister's best friend's sister is crazy about my sister. My sister isn't particularly fond of her. She (the best friend's sister) sticks to her like glue and has invited herself over to our house several times. She hasn't caught on to the subtle hints my sister has sent her. My sister isn't too awfully good at giving false excuses, but is afraid of hurting her feelings. Both of us just can't figure out what to do. What do you suggest?

A. False excuses do not work on glue. Besides, they create just as big a mess.

What your sister must say to the unwanted guest is, "I'm sorry, but this time Samantha and I just want to visit alone. I'll invite you some other time."

"Some other time," as all adults know, is a time that never arrives, but it is saved from the classification of "false" by being under the kinder and more useful category of "vague."

Feeling incorrect? Address your etiquette questions (in black or blue-black ink on white writing paper) to Miss Manners, in care of this newspaper.