Many times, people keep plodding along with an idea because no one has told them it's not good or viable or possible. And, many times, people give up on a great idea too soon because they didn't receive enough encouragement to keep going. When you have an idea, solicit feedback. Ask friends, family, and strangers what they think. And when you do, be crystal clear that you'd either like them to encourage you to see it through or criticize the idea in a very honest way.
You need to know whether to plow through or stop in your tracks.
Lots of kids on American Idol should have been told a long time ago by a parent or a friend that they're not good at singing. And I bet there are thousands of people who should have shown up to audition because they have a great singing voice but no one has told them.
It hurts to hear that your idea doesn't have merit or legs, but that pain is much duller than finding yourself bankrupt or hopeless because years of trying never paid off.
I've mentioned before that we all need cheerleaders. This is a great role for family and friends to play because it's a natural fit. But don't let their cheering voices drown out the handful of objective strangers that can tell you honestly whether or not your idea has a chance. When you get the meeting with the investor, the experienced entrepreneur, or the potential co-founder, before you pitch, ask them to be brutally honest whether or not your idea is worth chasing.
Then, they'll have your permission not to sugarcoat anything. And this is good. You don't need candy. You need the nutritious power of open and honest feedback.
What you don't want from anyone are polite smiles and nods. That doesn't tell you anything. You need someone to either jump on a couch or laugh in your face.