I've only just read the description.
She's clearly been chasing sheep, and the owners are hoping someone will take her on for a farm dog - otherwise I suspect she'll be on a one-way trip to the vet, or if she's lucky and they'll take her, the Dogs' Trust.
If you are an experienced trainer of working collies, just want a dog to work a few sheep on the farm, and you don't need it to be safe to leave loose while you're not watching, and don't want to spend money on a well-bred dog, it may be worth a look. I'd still check it out in terms of how it is with children, on the road, with cars, how it's recall is, and see it around sheep, before deciding. And, given the circs, I'd want a vet check too, to be sure it's clear of collie eye or any other problems.
In other words, I wouldn't touch it with a barge pole.