OK. That's believable. But that's not a system by which thieves allegedly leave signals for each other to show the level of danger (for them) in a house or how easy a particular house is to rob.
True. It was quite funny one time I went to the shop and I dropped a colourfull hair elastic out side my gate. When I came there was a bewildered bergie lady hanging around. When I picked it up her body language almost screamed "Oh, it just fell there" and she moved on. I'm sure if those signals were true they'd be pretty damn confusing for the best of thieves.