Founders

if you get solicited or unsolicited feedback about your pre-pmf product you should be ecstatic that someone cared

things to do:
- ask lots of questions and thank them
- don't need to explain anything

archetypes of not to do:

1. some founders/PMs take the high horse attitude of "oh you're too dumb to understand what the product is meant to do. let me ask some condescending questions to make you realize how dumb you are to understand my product".

2. some people get super defensive or on the back foot and start explaining all technical, resource and other reasons why things are the way they are. 
the common pitfall is to think the user asking you "why aren't things the way i want them". no. treat it as, they're telling you how they expect things to be.

Def agree these two archetypes are to be avoided.

One thing I find helpful is to also run your assumptions by potential users or customers.. it will enlighten you quickly if you are on track or not.

Don't do this up front, I usually do it at the point of discussion.. "Ahh so we put this here because we heard/thought you may want to x,y,z"