I could see vampires promoting misinformation in lore and fiction, just to throw victims off guard.
I can think of at least one novel in which the whole sunlight thing turns out to be a myth perpetuated by vampires for their own protection!
"Surprise, foolish mortals! Sunlight has no effect on us at all!"
Stuff also tends to slide in and out of the lore. To my knowledge, Stoker invented the turning-into-bats business, which was a staple of a vampire movies for generations, but that seems to have largely fallen out of vogue these days . . . .