"I don't see how this is spam, and I am surprised that people are offended that the authors of these info graphics are trying to make money."
They're doing so dishonestly. Dishonesty on the tubes is why so many of us are jaded and believe nothing.
Few of the examples said "Here's a professional infographic pandering to the current pop meme, surrounded by some monetizing ads", but instead it was "HERE IS MY FIRST INFOGRAPHIC!" (always ad free because that's a part of the bait-and-switch meme approach), and once it got boosted the URL turned to a 301 permanent PageRank forward to some spam factory, polluting search engines with garbage.
Meme herding itself is really the root cause, though: Once Digg showed a propensity for top N lists, the web became awash with vapid top N lists for everything, humorlessly produced by SEO drones.
Not all content follows this shallow, deceptive practice.
There is a dating site -- I honestly can't remember which one right now, and am not suppressing their name on purpose -- that keeps releasing compelling analysis data, predictably boosting them to the tops of all of the social news sites. In return for producing interesting content, they get lots of incoming hits and page rank goodness. Their motives are clear as day for everyone, and there is no surreptitious BS.
Sidenote: 99% of infographics are terrible.