I bought a scale that can tell your weight to the nearest 0.2 pounds,
and just for interest's sake, decided to try weighing myself
throughout the day to see how much a person's weight fluctuates
naturally.  (Among other things, this would mean that if I weighed
myself to see how much I'd lost on a diet, I'd have to include the
natural daily weight-fluctuation as a margin of error.)

But I keep seeing anomalies where I'll weigh myself two times about an
hour apart and see a difference of 0.6 or 0.8 pounds, even though I
haven't done anything (eating, drinking, sweating, or doing to the
bathroom) for the intervening hour that should change my weight.

At first I thought that was just the margin of error for the scale.
But if I weigh myself twice, one time immediately after the other, the
scale always gives the same reading.

So, either:
(a) the scale has a wide margin of error, but it somehow "remembers"
what you weighed 15 seconds ago (perhaps due to an anomaly in how it's
built, or perhaps deliberately in order to fool people who are doing
this in order to test the scale's accuracy :) ), so the fluctuations
don't show up in two successive weighings
or:
(b) I really can gain or lose up to 0.8 pounds in an hour of doing
nothing.  If that's the case, then how?  (My hair is dry at the
beginning and end of the interval so that's not it :) )