When DH and I were in London recently, sitting in a cafe in Oxford Street looking out of the window, we observed an obviously foreign little old lady who was begging away for all she was worth, approaching anybody who came within her radius, hand outstretched, eye contact etc. Later on, further down Oxford Street, we came across another similar little old lady doing the same.
Fairly obvious they were part of a begging business which used sympathetic figures like old women (and probably children).
But they are not the kind of beggars I was referring to. It's easy to spot a real desperate down and out.