Nick goes to visit Tom and Daisy early in the story after not having seen Tom since they shared some time together in college, many years before. Nick didn't know Tom well at that time, but was aware enough of his athletic accomplishments in college and of his family's wealth to be able to make some observations and comparisons.
Nick is not impressed with Tom at this point in his life. He describes Tom's appearance with words that sound almost confrontational: "a supercilious manner...arrogant eyes...always leaning aggressively forward...a cruel body." Aside from physical appearance, Tom's attire was not complimentary - "effeminate swank of his riding clothes" - and the sound of his voice supported "the impression of fractiousness" with a little "paternal contempt" added in.
Tom's attitude toward Nick - "I'm stronger and more of a man than you are" - does nothing to improve Nick's opinion. Tom's actions only add to the negative feelings Nick develops. Tom shows no interest in recognizing or learning more about Nick's employers; he interrupts Nick's conversation with Daisy before she can learn more about Nick's neighbor, Gatsby; Tom admits to being "a terrible pessimist" and displays racial prejudice backed with minimal knowledge of any reasons to support his views.
As Nick departs, he is feeling "confused and a little disgusted" at his cousin Daisy and her husband.