Critics of this online-only approach argue that only researching online sources misses critical influential individuals and inputs. They note that much influential exchange of information occurs in the offline world, and is not captured in online media. Indeed, the majority of consumer exchanges occurs face-to-face, not in an online environment, as evidenced by Carl. 

He notes that "an overwhelming majority of word-of-mouth (WOM) episodes (nearly 80%) ... occur in face-to-face interpersonal settings, while online WOM accounted for only seven to ten percent of the reported (WOM) episodes."

Carl concludes that "The majority of the WOM action still seems to be happening in the offline world. 

These findings are especially provocative since they emerge at a time when more and more organizations are paying attention to 

how their brands are discussed online and recent academic research has focused on online WOM. Thus it is important for organizations to keep both online and offline conversations on their radar screen."

Keller Fay announced in 2007 that "While experts have previously estimated that 80% of marketing-relevant word of mouth takes place “offline” (i.e., face-to-face or via telephone), the new results indicate that this figure is even higher – 92%." 

More recently, Nate Elliott at Forrester observed that "the huge majority of users influence each other face to face rather than through social online channels like blogs and social networks."[ 

And the Fluent report, though generally orientated towards online measures admits that "it is necessary to remember the effect that offline social activity has on purchasing decisions." It also notes that survey "respondents trust offline friends most, with 73 percent indicating near or complete trust versus just 33 percent for online friends."

With any Marketing Strategy, risks are involved. In recent months, there have been reports of brands dropping their influencers because of the controversies that surround them. One such influencer is famous YouTuber, PewDiePie, who made sensitive racial comments regarding specific communities. Brands therefore need to understand the type of social media influencers they engage with so as to minimise their risks and maximise their online investments.

Not all business influencers are equal. 

Some have more influence than others, and some mechanism of ranking is required, to distinguish between key influencers and less impactful people. 

A model for ranking business influencers has been developed by Influencer50, thus:

• Market reach – the number of people an individual has the ability to connect with.
• Independence – whether an influencer has a vested interest in promoting a particular point of view.
• Frequency of Impact – the number of opportunities an individual has to influence buying decisions.
• Expertise – how much of a subject matter expert is the influencer.
• Persuasiveness – the degree of consequence in ignoring an influencer's advice.
• Thoroughness of role – the extent to which influence is exerted across the decision lifecycle.

Several other companies including Ammo Marketing, Liquid Intelligence and DesignKarma Inc. in the US, Agent Wildfire in Canada, SCB Partners in Europe and Vocanic in Asia have developed their own proprietary 

Methodologies for identifying and targeting influencers for a market (or market sector).

Fred Reichheld, a consultant at Bain & Company, has developed a 

Methodology to determine the extent to which firms' growth is influenced by customers' propensity to make referrals to colleagues.

 Reichheld distills his research down to a single question: 

How likely is it that you would recommend company X to a friend or colleague?

 From answers to this question, a Net Promoter Score is determined, which correlates strongly with a firm's growth rate...

Sources of influencers can be varied. Marketers traditionally target influencers that are easy to identify, such as press, industry analysts and high profile executives. For most B2C purchases, however, influencers might include people known to the purchaser and the retailer staff. In higher value B2B transactions the community of influencers may be wide and varied, and include consultants, government-backed regulators, financiers and user communities.

Forrester analyst Michael Speyer notes that, for small and medium-size business, "IT sales are influenced by many parties, including peers, consultants, bloggers, and technology resellers".  He advises that "Vendors need to identify and characterize the influencers in their market. This requires a comprehensive influencer identification program and the establishment of criteria for ranking influencer impact on the decision process."

As well as a variety of influencer sources, influencers can play a variety of roles at different times in a decision process. This idea has been developed in Influencer Marketing by Brown & Hayes.  They map out how and when particular types of influencer affect the decision process. This then enables marketers to selectively target influencers depending on their individual profile of influence.

The influence of bloggers and other social media users is a topic of much discussion. This is covered in depth in Paul Gillin’s The New Influencers.  Brown & Hayes also cover the subject but are less convinced of the importance of the impact of social media, particularly in B2B settings.

Fake influencers have been around as long as real influencers have. All metrics that are used to determine the realness of an influencer account can be fabricated. 

Instagram has shut down third-party sites and apps which provide paid services to individual accounts for buying followers, likes, comments and more.

Despite these shutdowns, self hosted Instagram automation apps such as FollowLiker continue to evade Instagram legal threats and continue to thrive-