Season 1, Episode 12: Peggy comes into the office, which is trashed following the election night party. She is disgusted, removed, and upset. She doesn’t fit in.
Season 4, Episode 2: Peggy comes into the office, which is trashed following the Christmas party. She easily steps over the mess. She is at home, in command of her own space.
Thanks to Tom and Lorenzo, who sent me the screen caps I was having trouble getting.