In reply to LastBoyScout:
To be fair to them, it might be the only job they can get, and they may well think they are making a difference.
Personally, I don't blame the individuals (and am always nice, though assertive, in asking them to move out of the way). However I do blame the charities, and being accosted by a given charity's chugger causes me to be less likely to support that specific charity in future.
Neil