I agree that it's unfortunate about the skepticism, but I highly doubt that Mr. Beamon was on anything, let alone something that would allow that sort of "leap" (pun intended) in performance. I just always look back on that example as "proof" that outlier performances don't necessarily imply cheating.
Your story about walking off Beamon's jump is pretty funny. But, remember, even if you'd just walked off the previous world record in that event, it would've looked pretty shocking as well since it was "only" 2 feet shorter. I was a fairly mediocre high jumper in high school (although not really that bad for my height - I was only 5'7" to 5'8" at the time)...but I recall in practice setting the bar at the current world record and just staring up at the bar thinking "No freakin' way"...
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