Politico and other media outlets have pieces on the Gallup poll, which seems to average the guesstimates of their respondents to say that 51 percent of Federal tax dollars are wasted. Room for lots of ambiguity there: does "tax dollars" include FICA or Medicare taxes? What is "waste"--how many of our aircraft carrier groups are "waste"? So much ambiguity it's relatively meaningless, but it makes a good story.
As for me, if I stipulate that spending in accordance with legislation passed by Congress is not waste, my guesstimate is less than 5 percent waste, and even that is high.