I had assumed that taking off one's shoes when entering a house/dwelling of any sort was a given (unless explicitly told otherwise by the host).
I didn't say that my behavior is
common among Germans - it actually isn't AFAIK. But since you mention it, I would expect the host to tell me if he's
not OK with me keeping my shoes on. (Though having a look whether the host family's shoes are lined up in the entrance or stored out of sight, presumably in individuals' rooms, should give a first idea as well.)
Then again, they were from California where I imagine it's rare to have snow/mud/rain on your shoes that you wouldn't want to drag all over the floors...
Good point. I'm working in offices, going places by car, and most such places have a building entrance with a doormat and then the entrance to the flat (or equivalent) with
another doormat, so I'm not exactly creating farmland wherever I go.
Most Germans I've discussed the issue with weren't taken aback by my walking in with shoes in the first place but couldn't understand how someone wouldn't want to "get comfortable" the second the occasion presents itself.
(FWIW, the thing that'ld irritate
me would be an entrance without a doormat to clean my shoes before entering.)