"...I don't think it is necessarily unethical if you know that you can do it (so long as you can deliver before they start paying)" So the salesperson/founder

"...I don't think it is necessarily unethical if you know that you can do it (so long as you can deliver before they start paying)" So the salesperson/founder needs to have a good enough model of how the software works so that they know if a feature is relatively easy to provide, or if as another poster commented, it would require say a major change in a database design. I don't think it is necessarily unethical if you know that you can do it (so long as you can deliver before they start paying) When I was being sold to, I developed a good ear for phrases like 'in development' or 'that is just a custom report'. We used put it all in writing &c.