You should always use samples or demonstrations whenever possible.
It is far more effective to let people see and feel the items you are trying to sell them. Remember that the closer you get to having buyers' six senses involved, the better chance you have to closing the sale.
The number of people I see in my classes who still think people will be able to look at a proposal and determine the best job or service shocks me. Meeting with customers and explaining what they need must be done in person. The use of demos and samples allows you to separate yourself and maintain the profit levels you need.
There tons of stories of people who have proven the value of demos and samples being used in a sale. My favorite is one that happened to me many years ago. It could also help you. I was working for a heating and cooling manufacturer out of Utica, N.Y. They had good equipment but no name recognition. It was a big oil-heating market. There were 14 other manufacturers going after the same market. We needed to do something different - and effective. Our sales representative suggested mounting a furnace on a trailer with an oilcan.
Sometimes you have to ask yourself, "What is it going to take to convince this person to make a switch or at least try my product?" In the HVAC industry, often it is showing them and letting them feel and see the product.
In one of my classes in Chicago, an attendee talked about a technique he uses with homeowners. He uses it to sell not only the heating and air-conditioning equipment, but also his company. He truly feels that people buy him and his company first and the brand second.
That's the way I believe it should be. It ensures home-owners are involved in the sale and feel very comfortable with a contractor because he or she has made them part of the decision process. The last thing they're shown is the trailer that sits outside and where the ductwork for their job is designed.
Keep in mind that each time customers select an item they want, they are that much closer to signing the contract. The key point to remember is using samples and demos lets buyers get involved and share their opinions. That's the last step to making the sale.