what are the usual pitches these people make to relieve us of our
money or other things?
It's less about "pitches" than just keeping your valuables where fingers other than your own can't easily get to them: don't put anything you can't afford to lose in an exterior pocket or loosely secured purse. Wear a moneybelt or use another method of making it all but impossible for thief to get to the goods without your knowledge. Don't lay your cellphone down on cafe tables, sling any bag/purse with valuables off the back of a chair or set them by your feet.
Don't be distracted if approached by "survey takers" or other groups/individuals: keep moving.
Legally you're required to carry your passport at all times but we used to stow ours in the room safe in our hotel room - along with extra credit cards and bulk of our cash - and just carry copies. What with ever-increasing security concerns and checks these days, we have taken to having them on us more often, though. In your case, I think it's a good idea to carry them during the day; keep copies back at the hotel.