These scouting reports we are privy to often have inaccuracies because they only see the guys a few times, they don't have time to watch them all live either so it's mostly off video. It is also usually 1 set of eyes. So a shitty game ends up skewing these scouting reports.
Also when it comes to things like skating, these scouts will lose points for technique. Emile Poirier was a very quick skater, even had decent acceleration, but he was said to have "poor" skating, because his stride was unconventional and a bit awkward.
With NHL teams when they scout, they start scouting everywhere, then they single out players they like start scouting them more often and watch them several times and have a much deeper book on these guys. They also have other scouts check teh players out too, so more than one set of eyes see them.