Totally agree, we had a relative doing the exact same thing this Christmas eve while we were there. My Son (5) had put a feather boa round his Gran's dogs neck who quite happily let him. Because she will let him do whatever he likes within reason and he is very gentle with her as she is old. The DSIL who also had her 6 year old staffy who isnt the most cheerful dog as it is, with her. (Baring in mind my DS is the only child she will trust to be round it because he wont try to do silly things with it) and thats only with adults present. He has respect for animals.
It growls a lot at some of the kids when they get too hyper and is only allowed in the room with my son because he is so good with animals and quiet around them and knows the signs of a dog starting to get upset. She saw that my Son was dressing up Grans dog and wanted part of the action and to get a photo of the two dogs together. Then wondered why he started growling as she is trying to tie a scarf around his neck and put sunglasses on him, He definately wasnt gonna let her put anything on him or even get him next to the other dog who was wary now he was growling and had hidden behind the sofa. Then she wasnt happy when I refused to tell my son off for been "cheeky" to her, because she basically asked him to do it saying "Your so good with dogs, can you get him to wear them" and before I had a chance to say no my son replied "No, I wont he doesn't want to wear it and I wont blame him if he bites your nose off, he isnt happy and thats when dogs bite when they arent happy and they have silly owners" it really annoyed me and most of the other adults im the room who where all telling her to stop and she insisted "he just growls he wouldnt bite, he is soft as muck really" when one of my Uncles had told her the 5 year old had more sense than her. She ended up leaving early insisting that it was all down to the fact we didnt like him because he was a staffy. Not the issue clearly as the older dog is a staffy labradour cross and there are 4 other staffys in the family (not all living together). Two of which are the parents to her dog who was well trained before she took him on. I think some people just shouldnt have dogs if they cant look after them and respect the signs of an unhappy animal before they cause it to bite.