when i was a young teen with braces (and my little sis had them at the same time as i), i know i didn't take the BEST care of them... it just wasn't too big of a priority. my thoughts with this girl are that maybe she wasn't the best at caring for them, but IMO they don't look really bad. one of my thoughts was that her face, including mouth, was probably cleaned up after she was found. if she had an inconceivable amount of head trauma, etc.. it's very likely that she had some bleeding in the mouth and that could have discolored her bands and possibly stained the teeth. if her lips were part of the facial injuries, her lips would probably easily bleed by being pressed so hard against the braces. i also notice that she has "hook" brackets on a couple of her lower teeth that are showing. she most likely has 2 on her upper teeth too. these types of brackets are used to help in correcting an overbite. rubberbands connect from the bottom to the top hooks on each side. i had them on my teeth and my lips used to get torn to heck because they'd get caught on the hooks. i used lots of dental wax. i didn't have to wear the rubberbands the entire time, tho. man, i don't miss those days. but, i do remember them like they were yesterday.
all IMO, based on personal experience.