I dislike the Salvation Army for other reasons entirely and don't donate to them, but I have never had home made clothes rejected by a charity shop. They receive them stuffed into bags but I have often seen them out on the rails afterwards.
I did, however have a silk dress I had made rejected by a dry cleaner. Even when I told him what the content was and said I was prepared to take any risk, he flatly refused to accept it because it didn't have a label in it.