Everyone -- regardless of their inside footwear policy -- usually has a couple of shoes by the door, so this barely qualifies as a hint.
A lot of people suggest that if you just leave some shoes by the door, it is enough of hint that shoes-off is preferred. Ideally, people would take a hint, but in reality I don't think this will always happen. As akay points out, even people who don't have a shoes-off policy will often leave shoes by the door, so it is not really a hint.
