Should you see the hashtag #ad appear in a New Zealand tweet, do not mistake it for an overcautious declaration that the events described happened after the birth of Christ.

The hashtag is “required”, according to a newly published “guidance note on social media” from the Advertising Standards Authority, “if using paid-for Twitter endorsements”.

It’s debatable whether the guidelines (in PDF here), which apply from the start of next year, will have much of an impact. Especially given this from John Drinnan’s report in the Herald this morning:

ASA chief executive Hilary Souter said everybody who received money from advertisers was not obliged to include the hashtag #ad.

“It’s not black and white,” she said.

Indeed, grey areas abound.

Overseas examples such as footballers bigging up Nike are clear enough – these are advertising warranting declaration.

And it’s safe to assume – surely – that journalists tweeting attention to their own or colleagues’ work, or title accounts (such as the Listener’s) tweeting attention to contents that have gone online, fall outside the paid endorsement definition – even if you could argue that these are advertisements.

But there are other, murkier, areas.

In another recent UK example, bloggers got (and still get, I think) paid to watch a Sky News Sunday morning current affairs show and tweet about it, in an effort to drum up interest. They had no restrictions on what they tweeted, as long as they included the official hashtag. But aren’t they in effect paid endorsers of the show? Is it a form of advertising?

And celeb types, even some journalists, get sent stuff on a reasonably regular basis by people promoting their wares. When, for example, one of the Ridges, I forget which, and various others (including at least one journalist) excitedly tweeted pictures of the personalised Coke cans they’d been sent, should they have appended this with #ad? They’d arguably received payment in form of the gift – but does it amount to a “paid endorsement”?

One more: Promoters of shows are increasingly identifying “influential tweeters” and chucking free tickets their way. – the “tweet seats”, as I saw one Tweeter say the other day. There is not, as far as I know, any obligation to say positive things, but there is an implied expectation of enthusiastic tweeting, and recipients are advised of the hashtag to use. It’s all about building buzz, and probably a smart strategy, but does it amount to paying for endorsements? Hard to say.

Does money need to change hands? That would be strange and arbitrary: if you’re given a car and you tweet about loving said car, surely there you have a paid endorsement.

Rick Shera has touched on this in a more wide-ranging post on user-generated social media content and advertising, which he concludes this way:

If you’re reading a tweet which endorses a product, it makes a difference (to me anyway) knowing that the person got the product for free or was paid for the tweet.