If this has been discussed elsewhere, please direct me to the appropriate thread.

I'm interested in the reliability of oral history, and wondered whether anyone on here has investigated the family stories handed down to them, and what they had discovered as to the truth, falsity or twisted facts of these oral transmissions. How old were these stories, and how had they varied between collateral lines and over time?
I have three examples;
On my father's line he had a story from a cousin that their ancestor had fought a travelling pugilist at a fair and won the match, but the opponent died from his injuries. A more distant cousin had a version that this ancestor had been put up by his employer to participate in the fight and that he had won a pot of money from it (but no death involved).
Looking at where these different cousins joined up, it seemed this event must have occurred no later than the mid-nineteenth century. Eventually another cousin discovered the truth - in the mid nineteenth century two neighbouring villages were disputing about the ownership of a piece of land that lay between them. To resolve the issue each village put up two men to fight a boxing match - the winning village to take ownership of the plot of land. My ancestor was one of those men put forward, and he and his fellow boxer won the match, becoming minor local celebrities in the process. No deaths are recorded in the historical detail, nor any cash rewards, but it would be unusual if the locals hadn't placed bets on who was to win, and maybe my ancestor did gain money through it for it seems that shortly afterwards he went from being a farm labourer to being a farmer.
So this oral history survived 170 years, and whilst true in the main, gained some sensationalism and became two different variations.
Another example is from my mother's side.
My mother's mother and uncle believed they descended from a squire who's daughter ran away with the coachman while on her way to school in London. A distant cousin had a similar story, minus the London school, but adding that the squire altered his will so that only the daughters of his runaway daughter could inherit, and that this female inheritance tradition has continued in the family.
This was supposed to have happened in the early nineteenth century, and my researches have shown that the remembered localities of the events are correct, and that there is a connection with a family of 'independent means' (although on the groom's side rather than the bride), and, more curious, there is a tradition of the daughters, or daughters of daughters, in the family gaining inheritance over the sons (and some cousin-marriages that look as if they are trying to keep this inheritance in the male line).
Again truth in a story from 200 years before, but it seems garbled in some way that I have not yet discovered.
My final example is about a cup and saucer my grandmother gave me. She told me it was given to her by her paternal grandmother, who had it from
her grandmother. This takes the object back to before 1830, a date that fits well with the Regency period date given to it by an antique dealer. Unfortunately no anecdote is attached to the object.
I'd be interested to hear about your own researches into family stories, and how you either unraveled the truth, or got knotted in the details.