It's a term which has become familiar. Everyone knows what 'sex addiction' is, and the eye-rolling it tends to provoke is usually because of the celebrities and public figures who have cited it as the cause of their unreasonable sexual behaviour. Think of Russell Brand, David Duchovny. Rob Lowe and Michael Douglas (though he later denied it). Ryan Giggs is said to have agreed to undergo sex addiction therapy. When Tiger Woods was exposed as having multiple affairs, he went straight to therapy, spending 45 days as an in-patient. He reportedly underwent treatment for sex addiction, explaining in his statement to the press that he was "receiving guidance for the issues I'm facing". When the US Senator Anthony Weiner resigned in June after sending explicit photographs of himself to Twitter followers, the internet was abuzz with questions about whether he was a sex addict. When he asked for forgiveness for the "personal mistakes" he'd made to get the sexual highs that led to him losing the career he had fought hard to get, he was heckled, and shouts of "Pervert!" interrupted his speech. An admission of this kind is, it seems, difficult for an audience to take seriously. At the very least, there are raised eyebrows and sniggers; the most common reactions, to celebrities at least, are underpinned with cynicism.