Sorry but this guesstimate is a bit absurd. If the majority of ad clicks were ineffective or for wrong reasons, Google's $231 billion market cap would be tough to justify.
(1) A majority of Google is ~21% of total market.
(2) 79% of the total market is a Majority of the Market.
(3) 59% of the total market is a Majority of the Market.
and so forth...