I agree with you to a certain point but I still think you can dissect a typical London-look ... and that is what most of the age group 15-25 wears... it's very vintage inspired not afraid to mix prints often and very often a tan vintage bag.
They are in no way as crazy as the facehunter pictures as they are just taken in the East End/Shoreditch area..
I'm not saying they all dress like that but is very..shall I say..indie inspired.. I always feel like I am the only one drawn to a minimalistic sense of dressing..my mates don't really 'get' why I don't wear colours... in London I feel special but, actually..to my surprised missed standing out in Paris as in the chic areas everyone was wearing black!
It did get a tad dull... and coming home I actually had to put on an electric blue dress just to balance out my mood.
Is it weird while on holiday in Paris I was able to spot Londoners from miles away?