What I found very useful was a short list of checkpoints given by Robin on what he seeks in a start-up.
I've listed it here because I think it makes so much sense...
1. A team excited about what they're trying to achieve
2. A big vision with understanding of the issues involved in achieving it
3. A team that's already achieved a lot with very little
4. A differentiated product or service that meets a need
5. A project with global reach addressing a large market
There's one other point I would add for good measure; a business that can scale. By scale, I mean a business that will see exponentially increasing returns on the assets deployed as it grows.
Conclusion? If you are going to invest your heart and soul into a start up or join a start up team, make sure the answers to the above points are all "yes!"
Time will always tell course.
To the dealer, "I've made my bet and I'm sticking, thanks. I think I've been dealt a great hand".