That's why I always tell them to get an LOI. Often people will say, "that sounds great, let us know when it's ready", and the founder will mistakenly think that's a sale. Even asking someone to sign a non-binding LOI forces a lot more honesty.
This was one of the most helpful pieces of advice I ever got as a founder.
Pre-product, when customers would say "Yes, I would buy this," we asked them to sign a non-binding LOI to that effect.
Nowadays, if a prospect says they'll buy when we have feature X, we ask them to sign a modified customer contract that says they don't have to pay until we mutually agree that the feature is done.
It has saved countless developer months spent on features that were not the real reason the customer didn't want to buy. And it sometimes causes the prospect to start saying, "well, actually, the issue is..." and then you can get the real feedback.
Forcing to a yes or no is key. I prefer yes, can manage no, but I have no way to manage maybe, it just closes other options without delivering results.
