I am assuming that it depends on the nature of the project and the situation - if the team behind is working on finalizing the whitepaper so that they can upload it on the website- I wouldn't say that it's a scam. But then if there is no whitepaper at all, then I will assume that it's a scam. A whitepaper is meant to persuade the investors to invest in a certain start-up. What do you expect if your startup doesn't have a whitepaper- who do you think will ever invest their hardly earned money into your project - whereas they are not guaranteed that they will make a profit once the startup has a working product or not. I for one, wouldn't invest in such a project.