Well. I voted vacuum because that's what Eliza and Mozart are super terrified of... although ELiza is just as terrified of visitors..

I'm not sure what bach is scared of.. he follows the vacuum.. to make sure i get every single spot I guess.. but if it gets close to him.. he hits it LOL. Oh wait.. yes.. he is scared of baths.. doesn't matter if its wipes. or bath baths.. he HATES it!