Britney Spears will stand next to anything to get it for free. It's too bad she didn't stand next to a good set of extensions or a decent colorist. It's as picked up the walking corpse of straggly extension inkwell victim Lindsay Lohan and exclaimed - I WANT THIS!
There have been some internet theories about what that stain is. Did she change Sean Preston's diaper in the middle of the store and neglect to wipe the baby grease off her hands? And her fondness for dress grabbing/lifting has been documented (you must join ONTD in order to see that link, sorry, but it's too fantastic to leave behind). So that explanation seems likely, however, I actually think it's from a group of hair protesters who threw some highlight color at her and missed.
Initially, I was on the fence about Britney's new dark color - but that was when it was paired with shorter hair that Britney can actually maintain. This weak, long Morticia look needs to go, Brit. Wash your dress and wash it out.