One question I frequently get asked at my agency 1000heads is whether certain brands or industries are just too taboo to benefit from a word-of-mouth campaign.

Having worked with everything from tampons to nit shampoo, my answer is always no. I'm frequently amazed by what people are not only willing, but eager to discuss publicly; and our boundaries seem to be dissolving more each year.

A good example is healthcare. Pharma and medical companies have traditionally struggled to engage in social while navigating issues of confidentiality, competition and even embarrassment. But one of the big success stories of the spring was Facebook's collaboration with the UK and US organ donation services to encourage new donors to register and post on their Timelines. Fuelled by a sense of competitive do-goodery, Facebook users duly flooded the site with updates. One organisation in California reported a 700% increase in new donor registrations within hours.

A topic that still feels inappropriate for the dinner table had suddenly and unquestionably become a matter for public broadcast. Popular health communities such as WebMD and Rareshare have long relied upon moderation and anonymity to make users feel safe to share, but pushing medical details out to colleagues, strangers and even potential employers indicates a whole new level of permissiveness; 4.7 million people already 'like' a page about a health condition on Facebook and there are 2.6 million stories on walls about alcohol use.

Might it soon feel not just acceptable, but responsible, to share our diabetes or HIV status in our profile? Last year, I read about SeeMyOp, a social network and app which allowed people to livestream their surgery across Facebook, Twitter, Foursquare and Blippy. As far as I know, its developers are still looking for investors, but I have a worrying feeling they might not have to wait long.

We've seen this creeping erosion of boundaries happen in politics too. Most of us would still think twice before asking a stranger who they vote for. But in May's London elections, Twitter was awash with #voteken and #voteboris messages – allegiances that were once hidden by the ballot booth curtain were now on full display – and the US Presidential elections are relentlessly present across social networks.

When everyone is naming their chosen candidate, not joining in can feel like opting out of your public duty; a golden opportunity, you would think, for politicians and parties. But the actual influence of social media campaigning on voters has been questioned, and there can be difficult personal fallout too. Forgetting the Romney-loving nonsense a professional contact has been spewing when we next meet over the Pond is going to be a tough task.

This kind of dilemma is common in an ethical area composed of way more than 50 shades of grey. An open attitude to sharing can be a boon for businesses that operate in sensitive markets, but consumers' feelings about privacy are incredibly complex.

We kick up a verbal fuss at the thought of Google hawking information about our passions, behaviours and relationships, but still want the services that data pays for. Drop off Facebook? Sacrifice personalised search on Google? No way. More than 50% of consumers aged 18 to 34 say they would trade personal data in exchange for brand discounts. So much for integrity.

According to a recent Intel study, 90% of Americans believe that people share too much of themselves online. But, with that statistic clashing with the behaviour we're displaying, what approach should brands take?

Should they encourage sensitive and provocative conversations, but risk alienating more conservative customers? Should they take a stance of elegant restraint in order to rise above the crowd? Or can they make a killing by actively trampling remaining taboos into the ground, something Kotex has been doing brilliantly in its U by Kotex and Pinterest campaigns?

There's an old rule of thumb that works very well for social sharing, albeit with a little doctoring: don't say anything online you wouldn't be willing to say to someone's face. If you talk about health, politics or indeed period cramps on Twitter, you'd better be ready to discuss them with a customer, supplier or colleague on the street. Otherwise bravery starts to look an awful lot like posturing. And posturing is the one thing that social media hates.

This article originally appeared in the September 2012 issue of Admap. Click here for subscription information.