“Does the user obey the unwritten laws of adult Instagram, posting less than once a day, avoiding too many shots of their face, going easy on the hashtags? (Teen Instagram rules are different, if even more stringent). How are their vacations? Do they inspire envy in a way that’s beguiling, or merely crass? Are they eating in the right places? Instagram can seem like an index of mores in the age of self-branding and self-surveillance.”