I was reading dealarchitect today, and his Burning question is a very important one: Is software sold or bought?
An aggressive answer would say that sometimes we do indeed oversell products, or get companies to buy products that they are not in a position to use. Sometimes buyers will go through a long process of testing, proofing, and accepting a product and then it gets shelved until the key people are ready to implement it.
However before this ethics question is decided, one should ask is it the buyer or the seller at fault here? The seller spends a lot of time consulting and presenting, and needs a return on investment or else they would be doing something else.
It can be quite frustrating also for the seller when the buyer does buy something that seems to never get implemented. Although you (usually) don't give the money back, a part of selling requires reference customers who are able to honestly say how they use the product, and promote its use to new customers. If your product becomes shelfware, it will be noticeable to new prospects and can be damaging if word gets around.
On top of that, the business is unlikely to get upsell or continual revenue from that customer, and this is often key for a healthy ongoing revenue figure.
Part of the process of selling, therefore should include the incentive for the customer to use what they buy, and for them to be happy referenced customers.