My door attracts opposites, too – Telecomunication companies and charities

During my childhood I remember also at least one gypsie who asked if we have scissors and knifes to sharp.
Door to door sells are legal and there apparently are a couple companies who successfully sell goods and not just contracts to regular customers, although I haven't encountered them in my door frame.
But there are special laws to protect the customers from these salesmen. A customer can void a contract he signed in seven days.