There is a whole seedy underbelly to Twitter that I bet you know nothing about. It’s the shadowy Twitter follower black market: shifty websites and Twitter accounts offering thousands of followers or retweets for just a few dollars a pop.

And here’s another thing you may or may not know: one of the presidential candidates’ Twitter accounts might be a part of this underground Twitter economy.

Security firm Barracuda Labs went undercover to infiltrate the Twitter follower black market, and they compiled their findings into an info-packed infographic.

The firm created three Twitter accounts in May 2012. They used eBay and a website to purchase between 20,000 and 70,000 followers for each of these accounts, and then analysed each of the followers’ profiles and tweets.

The first surprise? It’s really, really easy – and cheap – to buy Twitter followers.

Of the top 100 Google results for the search term “buy Twitter followers”, there were 20 eBay sellers and 58 websites offering various types of fake followers for your hard-earned money.

…but not that much money. On average, 1,000 new (fake) Twitter followers will set you back a whopping $18.00.

Despite the low price tag per transaction, the sellers – or dealers as Barracuda Labs labels them – of Twitter followers can make a pretty penny doing what they do: the firm estimates that they can make up to $800/day for seven weeks of selling Twitter followers if they control 20,000 fake accounts. They also have the opportunity to use these fake accounts to sell retweets and other interactions, potentially skyrocketing their illicit daily profits into the quadruple digits.

To put a face on this underground Twitter economy, Barracuda Labs took a hard look at presidential candidate Mitt Romney’s 17 percent spike in new Twitter followers on July 21st.

They found that one quarter of these followers were less than 3 weeks old, and 80 percent were less than 90 days old. And, 10 percent have already been suspended by Twitter – not a good sign.

You can reach your own conclusions about whether someone in the Romney camp made the mistake of buying followers, whether it was his opponents trying to sabotage him, or whether this is all just a big coincidence.

The infographic about buying and selling Twitter followers is below, and you can read Barracuda Labs’ full report on their blog.

(Infographic courtesy of Barracuda Labs; Seedy people image via Shutterstock)