Ask Culture and Guess Culture
- points out some interesting differences of perspective among different people regarding what is polite or not. I'd probably instead call it "Ask Culture" versus "Beat-around-the-bush Culture" or maybe versus "Drop-hints-and-wait-to-be-offered Culture".
The MetaFilter post was regarding a specific situation: An acquaintance asking if they could stay at your house for a certain number of days.
Some people feel this is a perfectly acceptable question, and that one should simply reply "No" if one does not want to allow it (I think I fall into that category). Other people feel that even asking such a question is quite rude - that you can mention you'll be in town (and possibly hope that you may be offered a place to stay), but you should never directly ask the question, as that could put the other person in the "uncomfortable position of having to say no".
I suppose the latter people feel that their home is a sanctuary; sacrosanct; and that it is highly rude for anyone to ask to stay over unless they've first been invited to do so. Perhaps the discomfort with saying No is related to the culture valuing the appearance of graciousness and friendliness, but only up to a point which is assumed to be understood by everyone involved. Going beyond that point is seen as rude.
I doubt the "Ask" versus "Guess" thing applies to all questions, only certain kinds... perhaps only questions which could be considered to be asking for a favor. Surely the latter group feel it is okay to ask other things such as "Would you like to meet somewhere to eat dinner together while I'm in town?".
However, even the question about staying over at someone's house has many aspects to consider. It doesn't have to be considered a favor. Some people communicate very rarely, but still consider each other friends, and might still like to meet up with each other occasionally. Among some people, having someone they haven't seen in a long time stay over at their house could be seen as a great way to catch up with them, even if the main purpose of the other person's trip isn't to visit with them. Other people only feel friendly with people whom they remain in close contact with, and wouldn't consider having lesser acquaintances stay over. One person may see things from the one point of view, while the other person may see it from the other point of view.
Among some acquaintances, it may seem a natural thing that if they are traveling to your town, that you might offer them a place to stay, and that they'd reciprocate if you were traveling to their town.
Given how many friends and acquaintances a person may have, it may not be possible to remember which of those people have offered you a place to stay while visiting, versus those who haven't. With the "Guess" group of people, it seems you could only safely ask the question of close family members, even if other people had explicitly offered it to you in the past.
There may also be an issue with some people saying things like "We'd love to have you over sometime" without really meaning it. Don't some people say that simply out of politeness, not expecting the other person to ever take them up on the offer? And perhaps some people mean it in the sense of "I wouldn't mind you dropping by for an hour or so" while other people mean it in the sense of "I wouldn't mind you dropping by for a few days".
There will always be some people who might want to take advantage of you by getting a free place to stay, while not caring about you otherwise. Some people may pretend friendship and end up robbing you or worse. But simply asking if it is okay to stay over doesn't mean that the person is trying to take advantage.
This is all very theoretical for me. I haven't ever had a non-family member ask to stay at my house, nor have I ever asked to stay over at a non-family member's house. My perspective is based on my mom and her friends. When traveling, my mom has several times stayed with old friends, and old friends have occasionally visited her.