The "lore" in folklore originally refers to orally conveyed cultural knowledge and traditions. Either this orally conveyed information pre-dates that culture developing writing, or the "folk" (i.e. the common people) were not educated in the writing system.
Therefore, the generation and spreading of folklore that originiated in an oral tradition or the illiterate population of a culture is very similar to the generation and spreading of religious concepts, and in many cases they are arguably of the exact same origin. You can thus refer to the much larger body of literary crtiticism on religuous texts and apply their principles to folklore texts, as the principles and challenges will be very similar.
Anthropology and historical literary criticism have given us ample evidence that even when the oral stories were eventually written down, oral traditions are an extremely unreliable source for determining what the first oral original story was like. In the case of Christianity for example, we have found many (parts of) manuscripts that contradict each other. The New Testament has been preserved in more manuscripts than any other ancient work, having over 5,800 complete or fragmented Greek manuscripts, 10,000 Latin manuscripts and 9,300 manuscripts in various other ancient languages. You can take this as an analogy to how an internet technology based piece of folklore starts living its own life and how with every edition and comment it is distorted, they main difference being the timespan.
Another principle difference between oral and written information is that written information traditionally required contemplation, whereas oral communication is much more direct and influenced by emotions and preconceptions. Arguably, social network communication, even though it is written, is much closer to a direct emotional response than it is to a contemplative reaction. In this sense, you can find many parallels between anthropological studies of oral traditions and social network communications, the main difference being the verbatim "forward" option that oral traditions cannot reliably reproduce.