[bazil376]

And even if it wasn’t a good idea, the fact that the person couldn’t be respectful when they’re trying to impress you the most is a very bad sign.

[giantg2]

And you're not being hired as a product guy. You don't need marketable ideas. They could have dug into the technical architecture of it instead.

[kelnos]

Yeah, that's the thing. Being a dick to your interviewee -- being a dick to anyone -- is just a huge red flag.

And ignoring that, even if the project was just a toy that isn't particularly useful, that's not really the point. Developing and building a project/product from the ground up is useful experience, whatever it is. Demonstrating a valuable skill should never be a prompt for scorn.