An article "Using citations to Rank.." is an interesting read.
This article wonders how Veltech, a private university in Chennai, is ranked #1 in Asia on the basis of citations. The authors of that article should read this article.
Further, everyone keeps on changing the methodology. For example, the counting of "kilo-paper issue, papers mainly in particle physics with hundreds or thousands of authors and hundreds or thousands of citations." Read about it here.