I despise chuggers, utility sales people, religious zealots, no win no fee accident types, political activists, petition signature collectors etc. etc. Why? Because when I'm shopping, I'm shopping, and when I want to "shop" for any of the above I do so at a time of my choosing.
Can you imagine all the shopkeepers and retailers on your local high street following suit? They jump from the shadows, you try desperately not to establish eye contact (because then you have to talk don't you?), both of you briefly engaging in the military two step as you try to circle around them, all your efforts fail as you get blocked behind a slow moving pensioner with a tartan shopping trolly and your stalker delivers the line "Has sir thought about buying bananas recently or any hand foraged herbs, some wild garlic perhaps?" You would laugh and wonder if you were being secretly filmed wouldn't you?
But anyone from the preceding list is "normal" and we tolerate it. Personally I would love to walk the length of my local pedestrian precinct without being accosted by anyone from the above list.
And don't even get me started on buskers who's sole talent is painting their clothes and faces bronze and standing still :)