Earlier quoted context omitted.
I feel you, I also have this little voice that shouts "NO!" inside my head during meetings. But I've learned to say "I don't see it that way, but it's a good idea, let me think on that, please", which has won me a lot of respect. Even if my final answer is negative, the fact that I took some time to consider it is perceived as very positive by coworkers and managers.
There's another tactic too... one I use frequently for better or worse. So I see someone who says something I don't entirely agree with but I want to see where they are coming from. I start arguing with them, asking the harder questions, pointing out things I see as problems, not to push back or prove that I am right, but to prove the merit of their ideas. Sometimes I will say something to indicate why I am doing it,…
However, you can also wrap that in a friendly approach as youlost_thegame mentions - simply acknowledge the potential of the idea first (ie, positive energy) then go in with the tough questions.
I find even with friends and close colleagues, if I stick to the "nice first, then difficult questions combined with enthusiasm", I can often critique the idea while making the entire conversation positive. Often the faulty idea gets discarded by it's owner after consideration.