“I have this amazing Startup Idea that I want you to look at and tell me what you think. Can you sign this NDA first?”
Here’s why we will always say NO.

Over the years we have seen and heard hundreds of startups and hundreds more startup ideas.
Apart from the fact that a startup Idea is never thought of in a vacuum, there is always context, and you are never the only one with the same idea. (trust us on this)
There are also a lot of them, startup ideas have never been in more abundance than they are today.
startup Idea Universe
In Fact there is a vast Universe of Startup Ideas out there. Only a few of those Startup Ideas are plausible sounding Startup Ideas. Now Plausible sounding may seem like good Ideas, but in reality only a small portion of those actually are good Startup Ideas.
How can you make sure your idea is  part of that group?
Often Startups where one of the founders is ‘scratching his or her own itch’  have an advantage, as they are more likely to actually solve a real problem. As opposed to something that is ‘made up’ and sounds like a good idea to a lot of people that might want it. (Paul Graham explains this principle of ‘Made-up or sitcom’ Ideas here)
Startup Idea
Plausible ideas are ideas that sound like they are a good Idea, and when you go around and ask people, most will probably say they might like it. But if really put to the test, few will actually use it, or more important, actually pay for it because it is something a ‘nice to have’.
Always make sure you are building on a real NEED, or actual pain, even if to start with the customer segment seems smaller.
small group
With a real painkiller it is easier to validate, optimize and build your startup with the few means that you have. If that works, you can expand into world domination.