If she doesn't want to take advice now I don't think there would be any reason to believe she would later. Giving her more animals to mistreat I think would be a bit irresponsible. From the sounds of it she's been given advice many times and hasn't wanted to take it. Believe it or not I have ran across this before. With a random person it's probably best to keep your distance and steer clear of any animals they might have. You can offer your advice but expect them to take it with a grain of salt. But when someone is a friend it's hard to keep your distance for obvious reasons and in my experience they take it much more personal if you critique their husbandry unless they ask you for advice. This can cause issues in the friendship and it's hard to not say anything when you know the reasons why they are sick or thin when you feel so bad for the animals. It's sad when they are otherwise a really nice person. They just don't have a clue or care to put the time into reasearching the animals and think they know better just because "that's the way I've always done it and it's fine" even if they go through animals like M&Ms. It's sad but ultimately they are not your animals and there's really not much you can do about it.
*edit* I'm not sure where the thumbs down symbol came from but I don't see a way to remove it lol