I find it annoying when anyone challenges me or even questions me about a photo I am taking. However, I do believe that I should NOT infringe on anyone's rights in any manner whatsover. I would rather pass up a great photo than to stop or to hamper anyone else from that which they are entitled to do. I Make a strong point of avoiding stepping upon private property without permission. I try not to litter even in a minor fashion.
As I see it a rent a cop has the right to ask civil and appropriate questions. I have no right to impede anyone else from using the sidewalk with the way I setup my tripod and I make a point of not doing so. Of course if no one else is around to use the sidewalk then I set my tripod up as I choose. People who presume that they are welcome to interrupt what I am doing, with questions for example, are not treated very civilly...I have my rights too. If a person is going to attempt to stop me from taking a photo that I am legally allowed to take they are in for a rather hostile debate at the very least.