It might be worth talking to the anglers present first (if friendly enough), find out where they are fishing before you say why your there and then bait up the spots your keen on that they are not in, that way they can't really tell you not to bait up that spot as you know that they don't have a hook down there. They can of course claim that they have been baiting that spot as another option but at least you wont be baiting over their live hooks. Of course it does mean that after you leave you could find rigs being cast into your nicely baited spots.
Always a minefield baiting up when not fishing and staying on the right side of folk! If your an early riser getting up at the crack of dawn could help, I've noticed a lot of anglers doing nights that fall asleep and don't stir till 9 the next morning (unless they have a take).