Devious or Desperate?

This basically represents that conundrum when you see a homeless person (or even a Big Issue seller) directly plea for money. Now that you've been put on the spot, do you merely ignore them or immediately look for any spare change you have? My case is a strange one; i remember walking past a pair of 'homeless' people in Southport, only to see them rolling their sleeping bags up, counting their money and getting in their car on the way back. I'm not saying all homeless people are like this, but it makes you think...