I have been thinking about this, for ages. My mum keeps insisting in having a white lock on her sleek raven black hair. She is not a goth, her skin is not pale but olive and she doesn't wear black clothes...never! She is the typical latina who loves very! bright colours (such as lime green or bright orange) PUaghh..!. Umm.....I am not convinced. I don't know about her but what I know is that is a look that is hard to make work and it's high maintenance but actually, I reckon some people could pull it off, if:
1/ You are young, look young or even have a "young attitude"; in other words, if the white lock starts to look like you are not bother in covering your grey hair anymore, then it loses all its glamour. (Sorry, mum, I have decided it is going to be a "no").
2/I suspect it only goes with raven black hair, not with any other lighter shades or the contrast will lose its glory, although it would be interesting on deep red hair, too! (Remember Geri Halliwell from Spice Girls?).
3/I am not sure about the skintone, but I still think it looks best with fair skin colour although I have to tell you that one of my examples, Metal Sanaz (4th pic) looks great with it.
4/ It doesn't have to be platinum/white a la Daphne Guinness, I have noticed lots of rockabilly girls, such as Missy Malone (3rd pic) are adopting a more golden shade which I really like!