I have a tendency to at least talk a bit with people handing out pamphlets, asking for signatures or selling something, mostly because I've often been on their end. There's few things as demoralizing as going out, not asking much more of people than maybe a signature or accepting a pamphlet/argument for something one things is right, and 80% try to ignore it. People who stop and argue tend to be a welcome relief even, than apathy.