You should always be able to inform investors with anecdotes from like real users. If a founder can't come back, if I feel like I better understand the user than the founder does, that's a bad sign. The only way to get this kind of signal is to pitch a lot of investors. When everyone says the same thing, the takeaway still isn't believe that. It's assess it and dig into it.
Step inside the Group Partner Lounge to hear Y Combinator Group Partners Harj Taggar, Michael Seibel and Brad Flora discuss how you should handle rejection from investors and why you should "believe the no, not the why."
Apply to Y Combinator: https://www.ycombinator.com/apply/