Tim Walker: When tweet nothings turn sour

Tales from the water cooler...

I spent too much of this week negotiating the labyrinthine back corridors of Facebook, trying to alter my profile so that my online "friends" won't automatically be alerted whenever I read a scrap of celebrity tittle-tattle on The Independent website, or listen to a Justin Bieber song on Spotify (for research, okay?).

I was blasé about my privacy settings, but Facebook's present incarnation - which threatens to share my internet activity with the world, whether I want it to or not - finally has me worried. I shall be policing my profile with more caution from now on.

This must be how Ashton Kutcher feels. (Assuming celebrities have feelings, of course.) After years of tweeting intimate details from their marriage to a joint following that easily exceeds 10 million, reports suggest that Kutcher and Demi Moore have separated - and their Twitter feeds are near-silent on the matter.

Kutcher posted a Spotify link to "Don't Believe the Hype" by Public Enemy, followed by this riddle: "When you ASSUME to know that which you know nothing of you make an ASS out of U and ME".

Having been an implicit advocate of radical transparency, he has now retreated behind opaque rap lyrics and cryptic quotes.

When they were in the first flush of love, it must have seemed a fine idea for Kutcher to post photos of his wife's bikini-clad behind, or to have a good-natured online domestic after he'd publicly complained about their noisy neighbours - or, indeed, for Moore to name herself @mrskutcher. Whether their marriage is over or not, I expect they'll consider what they choose to share a little more carefully from now on. He who lives by the tweet...