I have almost recovered from submitting a grant proposal last week. When I was revising it, I realized that there's actually an easy way to tell how good one of your proposals is.
Nobody's going to believe your sales pitch unless you do. So, when you finish reading the introduction, do you get excited? Do you feel like pumping your fist and shouting "fuck yeah!" If so, then your proposal has the "fuck yeah" factor.
It's possible to get a proposal funded without the "fuck yeah" factor, e.g., maybe the competition is weak for that particular call, or maybe for once you draw a set of sympathetic reviewers. But why risk it?