If you are contemplating joining someone you've just met to start a company, there’s a tendency to use a ‘good idea filter’ on them. In many cases I’ve heard potential co-founders describe their meetings as “She was nice, we definitely clicked, I could work with her, but I’m not sure I buy her idea.” It seems like a lot of potential co-founders are looking for the so-obvious, lightning-strike idea and then, and only then, to connect together and start executing. Very few companies begin with such a foundation. Most ideas only seem obvious in hindsight.