In a nutshell as far as I understand it you need to expect a certain learning curve between you and your customers with regards to your product/service before it becomes sellable. In other words until you have let customers show you how they want to use your product and you have adapted to this reality, don’t bother traditional sales routes or funding.
In many ways this fits in with the whole agile approach of releasing early and changing even earlier.
Thus it is something to remember when bootstrapping. We bootstrappers are uniquely able to handle the Sales Learning Curve, but we need to be aware of it and not re-mortgage the house for 6 months living expenses to only find we haven’t got the sales we need at month 6 to keep in the game.