When I go to visit somebody, I always take the shoes off at the door, unless the lady of the house specifically tells me that it is OK to leave them on. When somebody visits us, we expect them to take off the shoes as soon as they enter our house. We even have a small bench right next to the door expressly for that purpose.
If somebody doesn’t take his shoes off, we probably won’t say anything (we are good hosts), especially if the shoes are clean, but we won’t like it.
Kiwi, to be on the safe side, I would suggest that if you visit any Canadians in their homes, you take your shoes off at the entrance.
Incidentally, in the third world it is customary to take your shoes off at the door. Even if you visit Hindu temple, or a mosque, they expect you to remove your shoes when you enter.
I remember when President Carter visited India, he visited a Hindu temple. But of course, you don’t ask the President to take off his shoes. So they gave him specially made silk slippers to wear (on top of his shoes). If silk touched the floor of the temple, it is no big deal, silk is cloth. But I think such exceptions are made only for Presidents. Everybody else takes their shoes off.
Anyway, I think it is only good manners to remove ones shoes when one visits somebody. Even most tradesmen who enter our house take off their shoes without us asking them.
So remember, to be on the safe side, remove the shoes.