The problem with "asking for the brutal truth" is that no one knows what it is.
At least in terms new markets and new products, you are facing the unknown. You can't work it out in your head; you can't find the right person to tell you if it's right or it's wrong. You just have to try it.
Don't be fooled when confident VCs and angels act like they know; they don't. They're just guessing (that's their job).
Far better to encourage an experimental approach: to be encouraged to try things and to be encouraged when it doesn't work. Because courage is what you need to face the unknown.
It is useful to be exposed to many perspectives, for new ways to think about things. It's useful to learn facts about the space you're in (doing your best to distinguish between fact and opinion). It's useful to discuss ideas, possible problems and opportunities - but not in terms of judging your idea, but in terms of seeing what's there.
With knowledge and experience of reality, you will develop your own sense of what will work. You still won't know, of course; but you'll be more confident of trying it.
The problem with "asking for the brutal truth" is that no one knows what it is.
Users know, in the sense that they embody it. That's one reason it's good to launch quickly: so that users can tell you precisely how far along you are with the idea.
However a specific group of users does not necessarily embody "the truth" either. An example of this is being captive to customers, as in the innovator's dilemma. Listening to the wrong group of users can lead you in the wrong direction. Sometimes you have to select who to listen to - something that users can't tell you.
Of course, who cares if it's "the truth" or not? Users are users, and approximate feedback is better than none, even if it is not precisely "true".
At least in terms new markets and new products, you are facing the unknown. You can't work it out in your head; you can't find the right person to tell you if it's right or it's wrong. You just have to try it.
Don't be fooled when confident VCs and angels act like they know; they don't. They're just guessing (that's their job).
Far better to encourage an experimental approach: to be encouraged to try things and to be encouraged when it doesn't work. Because courage is what you need to face the unknown.
It is useful to be exposed to many perspectives, for new ways to think about things. It's useful to learn facts about the space you're in (doing your best to distinguish between fact and opinion). It's useful to discuss ideas, possible problems and opportunities - but not in terms of judging your idea, but in terms of seeing what's there.
With knowledge and experience of reality, you will develop your own sense of what will work. You still won't know, of course; but you'll be more confident of trying it.