Is paying people 4x market wage to make road repairs wasteful?
Is research on squirrel mating wasteful?
And honestly, even if we could agree on these things, which we can't, that's not where our spending troubles lie. At least on a federal level, it's social security, medicare, medicaid and military spending. This is a whopping 75% of the Federal Budget. I can stop the university biologists from researching the amorous habits of our bushy tailed friends, and I will be praised for it. But, this doesn't really solve anything.
And no candidate is saying "I'm going to cut every bit of wasteful military spending and help re-think the long-term fiscal outlook for our social welfare programs."
Because that's scary. Even if some military spending is wasteful or unnecessary, someone's currently making the planes and bombs. And they're going to be mad you're cutting their gig. And your opponent can say we're so much less safe because of it. But, it's the very thing that must be said.