Just went through a Facebook ordeal myself. I am doing a favor for a friend and photographing her son's wedding in December. I was up to their house one day, and they asked me about doing a quick Impromptu engagement session. I agreed, and the mother of the groom took the photo's, and of course put them on her Facebook. She did give me credit for the images, as she loves the work I do, and mentions me all the time to people. However the bride to be shared them on her Facebook page, and now she and her friends are editing them themselves, and posting them saying that "it looks better like this". I politely private messaged the bride asking them to not do this, and the Mother of the groom then says to me "You Photographers need to get over yourselves". Then she goes on to inform me that Photographers copyright was developed as a "get rich quick" scheme by photographers who can't cut it. She then says, "My husband goes on the internet and downloads photo's all the time that he want's, and if they have a watermark he just removes it so he can use it for himself".
Fortunately the bride understands where I'm coming from, and the editing of my photo's has stopped. I am not making a living off my photography, and as such I don't care if people share the photo's around Facebook so long as I get some credit. However the mother of the groom who are actually my "friends" has annoyed me to no end, and I really don't think that I'll be doing any further work for them after this wedding.