I've heard the "personality" that a lot of major sites use referred to as "the new sincerity," because apparently, somehow, "sincere" meant endlessly chipper and painfully patronizing.
[1] Dividing their market capitalization, as an estimate of their discounted future cash flows, by their number of users. A better estimate might be smaller, if their user base is expected to grow or they are expected to make lots of money in some other business