I asked this question about zero-mean noise on Physics Stack Exchange and got this answer:
Zero mean so that the noise does not present a net disturbance to the system. There's as much positive noise as negative, so they cancel out in the long run. If the mean were not zero, then the noise would appear as an additional dynamic. For example, if the quantity were a force with some random jitter to it, then if the jitter did not have zero mean, the noise would appear as an additional net force on average.
I can't understand the meaning of the answer. What is another example of zero-mean noise, with an explanation from this answer?