It really depends on you relationship with the person, doesn't it? If it's a casual acquaintance, or even if it's a good friend who is known for being emotional, why should I expose myself to their potential anger when I say their idea sucks? I can be as careful as I want with my tone of voice and picking confrontational, constructive language, but there's still a chance they'll take offense and blow up at me.

What's in it for me? If someone wants me to think hard about their thing, and make a serious effort to communicate my thoughts about it, they have to earn it with trust. It's their own responsibility to research their idea and get honest, informed opinions about whether it will work or not. It's not my responsibility to be their mom.

Great post. I've been guilty of this at times and will try hard to stop. It's hard to strike a balance on knowing when a person just needs to try and idea and when they should really reconsider it entirely. Also, I would have told the founders of Twitter that I think their idea is stupid and that no one is going to post 140 characters about their breakfast. I would have been wrong to be discouraging. I guess the key is "constructive" feedback, this no matter what your overall opinion of the idea can help point them in the right direction.

I've been grinfucked so many times in my life... and I've done it myself just as many. Being confrontational and instructive is hard. Being polite and unopinionated is easy. =(

Cool design, bro.