[quote=@Bright_Ops]
...Why would wearing the flayed skin of a mortal protect him beyond creating a minor barrier between his flesh and daylight? Why was [i]that[/i] the first thing you thought of? 
[/quote]

Isn't it obvious? It's a mystical way widely spread in media in which vampires countered their weakness. Thick clothing does not protect them from sun, their eyes boil if they look directly at the hateful star, they are mystically compelled to slumber during the day, but if they wear a flayed skin of a still-living mortal that is taken off without missing even a single centimeter, they can walk under the sun for a single day without trouble. The mortal however takes the brunt of the bloodsucker's curse and dies quickly after. 
Same shit as a special potion that makes a vampire forget that he is cursed for a single day, which mystically makes them immune to the curse they forget about.

Though in actuality, to be completely honest most of original folklores don't really give vampires a weakness to sunlight - they are simply nocturnal predators. Garlic, too, is completely ineffective because one is supposed to use the FLOWERS, not the garlic bulb. The only thing that truly persists through all stories is the staking and the fact that most vampires grow a monobrow.