They have control groups, and when it's not expensive they repeat the trials many times. Oh, you assumed because they show one trial that their "estimated velocity" and such are actually based on one trial and not 10 or 20? Wrong. Assuming something just because you saw no direct evidence isn't very scientific of you! The only problem is they only have 3 classifications for their results. They have sure and unsure confirmations, but no unsure refutation. That is, they're missing "Could Not Reproduce" or "Implausible" for things which they cannot pull off, and have legitimate theoretical/mathematical backing to say are unlikely. Technically most of the things they "Bust" actually belong to that unused category because you can't conclusively prove a negative through trial, and they end up being retested and actually being possible. But they make that pretty clear, that "Busted" doesn't mean impossible, just that not only could they not do it, but also that they think there's reason to believe that nobody could. And they often revisit "Busted" myths and confirm them, though usually that has to do with changing the myth (or their interpretation of what it means) rather than just trying the same thing some more. For example, when they revisited the "bullet through the scope" myth they tried it with an old WWII era scope. In their first trials they found that even armor piercing rounds didn't have the force to penetrate all of the lenses in a modern scope so they called it busted (even if by luck it could happen very rarely). But with the old scope with less glass in the way, they pulled it off right away. Both conclusions are correct, though it comes down to number of trials and what "sigma" it means to say "Busted". But that's just wordplay. It was still a scientific experiment, just with poorly-defined words in the conclusions. And they usually don't show us all of their trials and all of their figures, so we can't do our own calculations for the error bars. At any rate, if a sharpshooter hits a scope dead center 10 times and every time the bullet is deflected by the lenses, then even if you object to calling that "impossible" instead of "unlikely" it does bust the myth that it's a good idea to aim at the scope instead of the person behind it.