Nick already has begun to develop a dislike for Tom. In Chapter 1, Tom reveals himself to be a brute racist. In Chapter 2, Tom confirms that he is having an affair. When Nick meets Myrtle, one of the first things he notices is how poorly she treats her own husband, Mr. Wilson. Then, on the way to the party, she buys a gossip magazine, some makeup, and a dog, all for superficial reasons. Myrtle's sister, Catherine, has bracelets that make an incessant clicking sound whenever she moves, as if to call attention to the jewelry. Mrs. McKee is "shrill, languid, handsome, and horrible." She also brags of being photographed by her husband. With the exception of Mr. McKee, everyone seems superficial, pretentious, and fake.
Even the apartment is too adorned with superfluous flair:
The living-room was crowded to the doors with a set of tapestried furniture entirely too large for it, so that to move about was to stumble continually over scenes of ladies swinging in the gardens of Versailles.
At one point, Catherine tells Nick that neither Tom nor Myrtle can stand who they are married to. Catherine is making assumptions here but the fact is that these marriages are not perfect. Nick is ambivalent because while he really doesn't want to spend time with Tom, he is accommodating and then genuinely wondered about Tom's mistress. "Though I was curious to see her, I had no desire to meet her—but I did." By the time Tom hits Myrtle, Nick is no longer ambivalent. He is annoyed and thankful to leave the party. Note that Nick claims to have been drunk only twice in his life. Perhaps getting drunk was his way of numbing himself so he could deal with these people.