There's a difference between the OP's situation and a new car model Greg, I think. A new car model is like a conventional oil well: you use the best models and data you can to pick the right place to drill, but only a few of them pay out like gangbusters.
No, I suspect that the situation the OP is talking about is, to use an example from my industry, an idea for a new chemical process to make C starting with A and B, where the cost of railcar quantities of A and B is higher than the market price of railcar quantities of pure C. A project which is dead before it's born- one which even the remotest bit of analytical thought would have killed before the mouth was opened to suggest it, but regrettably that thought never happened.
Unfortunately some of us can't help but notice when the emperor's new clothes are a little skimpy. Worse still, we can't help but point this out, or at least to be unable to shrug and smile and admire what isn't there- or pretend that we don't see what is there.
This fact makes me the wrong guy for the job on many projects. It also makes me the right guy for the job for some clients, and those people ask for me my name. There are enough of the latter people to keep me in my job, or at least there have been so far.
I've had delighted clients whose projects never made a gram of product- an exciting idea proved unworthy of investment for reasons not apparent at the outset, despite thorough work at every step. I've also seen projects which were considered successful by their proponents despite not being a commercial or technical success, because they attracted sufficient funding and built a base of IP etc. to draw on. So it is very easy to conclude too early that something isn't worth doing at all without realizing that your idea of "worth doing" may differ from that of your client or employer. I have to be careful to remember this, but I can't refrain from asking the tough questions- it's in my nature.
I've been with my employer for a couple decades, and I own a piece of the company. Whenever my money is about to be spent on what I consider to be a boondoggle, you can hear my opinion from across the building. Doesn't mean there aren't boondoggles that escape my notice (many are considered above my pay grade, for which I'm supposed to be thankful and probably should be).