Wow, there are some people getting highly upset about this! It is clear that AC very often has to be pushed to do something about very obvious abuse and neglect cases so I can imagine the difficulties surrounding a borderline case of abuse and neglect. Just because AC visited once does not mean there is not a problem.
The fact of the matter here is that EVERYONE is speculating. The person that has the most information about these horses is the original poster. She needs to trust her gut and if she feels she should, she should either contact someone else or keep bugging AC. Standing in manure is not OK in a stall so why would it ever be ok for outside??? She should err on the side of caution and for the sake of all animals do what she thinks is right. I am grateful that more and more people refuse to turn a blind eye and do what is right instead of "minding their own business". And no, she should not approach these people. She should let the authorities or someone that has been trained for this sort of thing do that.