"Wow, that looks great! So excited for you!" is also an acceptable response.
In all seriousness, the shampoo we have acquired for our pigs is from Gorgeous Guineas which, as you may or may not be aware, is made specifically for guinea pigs and comes highly recommended from many guinea pig owners. I personally believe that giving piggies regular baths helps to keep them clean in areas they may not be as good at cleaning themselves, such as grease glands.
Our pigs have never had any issues with the pigloos aside from just not liking them as much as other hiddes. Presumably because they are see through and so even when inside they still don't feel entirely safe. This is one of many reasons I would like to phase them out eventually. That being said, I would never pair together piggies who would harm each other. Pigloo or not. Period. Besides, the rescue I got them from wouldn't allow it even if I did.