Median does not represent the measure of such series of which different values are wide apart from each other.
For example, in a sample 1, 3, 17, 100, 200, the median (middlemost value) is 17, which doesn't take actual values into account.
So, degree of variability is high (median is 17, but values stretches upto 200).
Hence, the median is not a representative central data.
As a consequence, mean deviation about median calculated for such a series cannot be fully relied.