Everyone has had to work on a project that was a bad idea from the start. But since the Bad Idea was championed by Someone Important, the group had to spend time and money to prove it was a bad idea.
Perhaps there was a kernel of a good idea within it that could be sorted from he ashes of failure, but that’s an expensive way to get to the Good Idea.
On the other end of the spectrum is the Good Idea that you are afraid to try because it hasn’t “Gone Through Channels” or “Been Reviewed by the Idea Committee”.
Do it anyway. Be your own champion. Even if it doesn’t work out, you will be setting yourself apart as someone who is willing to take the right kind of risks, and they are the people who get promoted.