Yesterday I sat down for a lengthy conversation with the social media heads of three of the biggest PR firms in the world. The discussion was conducted according to Chatham House rules, so I cannot reveal their names. The desire for anonymity is probably not surprising, given the frank nature of their comments. In particular, I asked what their biggest gripes were regarding their roles. And here, in no particular order, they are: 1. "Investing ahead of the curve." In particular, this person pointed out that digital growth, by definition, is buoyant. The bigger challenge is convincing satisfied market heads that it can be accelerated even further through judicious investment. It may call for a multiplier model, but remains a tough case to make. 2. "Digital conversion". The idea that everyone within a firm should have some basic level of digital proficiency seems fairly self-evident. However, it also requires a considerable commitment to the training required for this conversion, which is not always forthcoming. Of particular concern, noted the social media head, are "CEO holdouts" who simply don't accept the rationale for their own particular market. 3. "Hiring". In and of itself, hiring digital talent remains a critical problem. But hiring in a booming market, where digital business is not difficult to come by, adds another layer of complexity to the issue. In particular, said this digital director, agencies remain unwilling to make suitably aggressive hiring decisions, opting for a needlessly conservative mindset that often asks: "How do you know you'll win that much next month?" You may have noticed that all three of these concerns revolve around the same fundamental issue. A few years ago, I wondered whether there was enough social media business for PR firms to justify the hype. That does not seem to be in question anymore. Weber Shandwick CEO Harris Diamond regularly points out that digital business - whether content creation, community management, or analytics - is "additive". Yet it can still be difficult for heads of social media (at the biggest firms, no less) to justify increased investment, particularly at the all-important local market level. As one of the executives put it, behaviour can match that neat description of insanity: "Doing the same thing again and again, and expecting a different outcome." What about you? Does this chime with your experiences of social media investment and spending?