Stock 340 dyno tests?

To me it seem like some track guys have dyno trust issues, guess cause a dyno operators can fudge the results bit, and I guess from a bunch of braggarts that say they dyno X hp but come up far short of that on the track, can't really fudge an et/mph. But is ridiculous to trash dynos as an unreliable tool, I imagine anyone serious about their engine doesn't wants fake unreliable dyno results.