People generally do not want to cause a fuss so, as long as you can hide the recorder quickly, walking towards the lift/stairs whilst smiling and saying 'hi' (especially late at night) is enough. It works for me, anyway. Act like you have every right to be there (which you do!) and whatever you do don't look like a perv.
The other thing that people generally don't do is to come out of their rooms at night - especially when they are having fun. Well, I say that but you do get the odd exception. There was the couple I heard fucking, late at night, in the public areas of one particular hotel (including in the corridor right outside my room, believe it or not!) Pre-recorder, sadly, so no catch to prove it. Just occasionally we aren't the only pervs outside our rooms at night.
