The legions of f^cktards that take advantage of others acts of kindness and have made most of us more skeptical and hardened so that when somebody genuinely needs assistance we're hesitant to do anything for them. Examples are scam artist repair people, boiler room operations that especially pray on the elderly, bums that claim to need food but drink or smoke up their spare change, countless phony requests for charity and so many more.
These people have always existed and are a plague upon humanity.