marketing

I want to jump in with a question in regards to "Direct Marketing". Is it unprofessional to approach customers directly and offer your services with a business card? I.E during normal daytime hours, ringing their door bell, starting a conversation, offering your business, and then leaving a business card or flyer so that they can decide by themselves without you being there. I know people get intimidated when you position it as a yes or no question right up front. However leaving the flyer or card will allow them the comfort and convenience of calling you when and IF they want to use your service. Thanks.