Misinformation travels faster than reliable information. This has been shown time and time again. For example, in their work published in Science two years ago, M.I.T. researchers investigated around 126,000 stories tweeted by around 3 million people and classified news as true or false using information from six independent fact-checking organisations. They showed that falsehood diffused significantly faster than the truth in all categories of information”. Specifically, “it took the truth about six times as long as falsehood to reach 1500 people” and “20 times as long as falsehood to reach a cascade depth of 10”.
In contrast, posts from individuals or organisations that are experts in a topic are not necessarily popular in social media. For example, when researchers analysed the content and source of the most popular tweets for a case of diphtheria in Spain, none of the popular tweets were posted by healthcare organisations. They were mainly opinions from non-experts.
This by no means indicates that a viral post is misinformation just because it is viral, but it certainly is a reason to think twice before reposting.
Vosoughi, S., Roy, D. and Aral, S., 2018. The spread of true and false news online. Science, 359(6380), pp.1146-1151.
Porat, T., Garaizar, P., Ferrero, M., Jones, H., Ashworth, M. and Vadillo, M.A., 2019. Content and source analysis of popular tweets following a recent case of diphtheria in Spain. European journal of public health, 29(1), pp.117-122.