I tend to agree with dasNdanger's last post to an extent... I *do* my research, and then go from there. I try to remain *plausibly* period, but I stick to my personal preferences too. I carry my persona well, and everyone in my circle can tell instantly that I'm a pirate... I throw elements of fantasy in, so the earring thing is an interesting conundrum for me. I suspect that it was a common thing, partly because all myths have at least some basis in fact. I also know that I would be more or less the same person 300 years ago as I am now... a little less educated to be sure, but I feel that my persona would have worn them, so I wear them.
But then again, the SCA is a game played for one's own enjoyment than for the entertainment of the general populace.