The Real Name policy was the beginning of the end for me, Reader being shut down made me lose interest in all new Google products, and Snowden made me stop using some of the ones I already had been.
The Real Name policy is noteworthy from starting out being fundamentally stupid at the "anyone who has spent a week online should know this" level, but still seemingly just a dumb mistake, to being downright malicious and evil the moment it was clear they had no intention of backtracking even after their attention had been brought to the risks it put some people in.