If it is a quality promotional product that you are happy with and which does a good job then its more then likely that you will be pleased with that company even though you may have never even been one of their customers. By getting your own promotional products made up and handed out to potential customers in your area you could really be increasing your customer base as well as feeling that you have contributed to your local community.
One other popular choice for companies to promote themselves through promotional products is by using golf shirts embroidered with the name of a company on them. Golf appeals mainly to quite a specific group of people, and is a sport that is mainly taken up by quite wealthy people, usually businessmen, and so companies can use golf shirts to appeal to quite a niche market. Golf shirts embroidered with the name of a company will usually also contain a contact detail and maybe the subject of their business, such as tailors or market researchers.