As long as the sampling isn't skewed, and is properly random and covers the whole space evenly, it will estimate cardinality correctly regardless of the underly

As long as the sampling isn't skewed, and is properly random and covers the whole space evenly, it will estimate cardinality correctly regardless of the underlying distribution. There is no way for clustering to alter the probability of a hit or a miss. There is nowhere to "hide". The probability of a hit remains the proportion of the space which is filled.