When I was growing up, I had a friend named Stephen Tu. As you may surmise from his last name, he's of asian extraction. Those of you who though he was ancient roman may excuse yourselves. Anyways, his house was the first one I encountered where one was very specifically instructed to remove one's shoes at the entry of the house. As I mentioned, I was very young, so the idea was quite novel. Hell, I could barely be bothered to slam screen doors as I passed into and out of houses like a particularly destructive zephyr, so the no-nonsense way in which I was told to stop and remove my shoes left a marked impression on me.
Now, as a more-or-less adult, I find that I take my shoes off upon entering houses. Mine or other people's, it makes little difference. No one ever seems offended by it, which upon reflection is a bit odd. I suppose it is seen as a gesture of respect ("I must not dishonor your floors with dirt and/or possible shoe-inflicted damage"), as compared to a means of airing out both my shoes and my feet at the expense of the resident ("Man, look at that vapor!"). Anyways, no one seems to object.
And, although this could be seen as a function of my near-constant Birkenstock wearing (note: I capitalized 'Birkenstock', but not 'roman' or 'asian'. I know what side my orthopedic bread is buttered on.), I do the same thing even if in other shoes. So it's not just the ease with which they come off.
It's not that I am particularly a believer in the evils of indoor shoes. I certainly never demand that guests remove their shoes. I just don't care, at least not on a conscious level. But it seems silly to me to bother to differentiate the inside of the house with carpet and suchlike if you aren't going to use it. Come to think of it, I like to lie on the floor, too. Hmm. Maybe I do care. Take those dirty fucking things off!
Carpet has to be one of civilization's better advances. Sure, the whole 'rug' thing dates back to the cavemen, who quickly claimed the invention of 'shag' once they discovered that bears lacked patent attorneys. And once weaving was discovered and we could move out of our dependance on dead animal based technology, we swiftly discovered carpets and blankets and a new sort of rug that bore less resemblance to Bobcat Goldthwait's hair. But it wasn't until very recently that we were able to effectively clean the carpet in situ, thus allowing us to staple down the floor covering permanently.
At least, some people can effectively clean the carpet. Somehow my vacuums always end up making hideous, Exorcist-based noises and feebly pushing the dust bunnies around some. I hope getting married will take care of this problem, either by endowing me with magical homeowner competence or by my wife being able to summon the vacuum fairy. Either way is good by me.
Some people don't go in for carpet, because they are perverts. Now, I admit, for a kitchen you want tile, or if you tend to drop heavy things, linoleum, but you hardwood floor affectionadoes are just plain odd. Embrace rug doctor technology! Sure, it's pretty, but frankly that ol' vestigial tailbone just doesn't like a hard floor. Satiate your wood panelling needs with the walls and/or ceiling! Wood floors scratch and dent far too easily, too. Much more satisfactory to have a strange dimple in the carpet that guests can only feel than to have an unsightly triangular notch from where you dropped that filing cabinet you were trying to shake open. And what about juggling knives? Drop them on carpet - no problem! Drop them on hardwood floors? It looks like Norman Bates is in your basement, trying to get you to shut up.
Carpet - it hides a myriad of sins. If I come over and don't take off my shoes, it's not because my feet stink - it's because I am very deliberately disrespecting your cold, archaic, antisocial wooden floor.
Or because I saw the knife marks.