Tom clearly resents Gatsby and has only contempt for him. He scorns Gatsby's intrusion into his "perfect" world and the fact that he, the supercilious man that he is, can be made to feel so insecure and uncertain.
Chapter 7 best illustrates Tom's intense dislike. When he sees Daisy's flirtatious behaviour with Gatsby and the manner in which she defends him, he reacts in a blatantly contemptuous manner.
His references are rich with metaphors which illustrate his disdain for Gatsby. He, for example, refers to Gatsby's car as a "circus wagon" and he makes a scornful reference to the fact that Gatsby wears a "pink suit." When he informs Jordan Baker that he has a done little investigation into Gatsby and has heard about his being at Oxford, he remarks that it might have been "Oxford, New Mexico," casting doubt on the veracity of Gatsby's claim of having been a student at Oxford University. He later challenges Gatsby about this claim and mocks Gatsby's use of the expression "old sport."
Tom refers to Gatsby as "this fellow" as if he means absolutely nothing. He questions the relationship Gatsby had with Daisy before he met her by saying he "knew her before we were married, God knows where!" intimating that Gatsby could only have had some relationship with Daisy in a place or circumstances forsaken by God. He furthermore suggests that Gatsby could only have had contact with Daisy if he had "delivered groceries to the back door." He would be "damned to see that he got within a mile of her." All this clearly suggests that Tom thinks nothing of Gatsby and sees him as trash - unworthy of Daisy's attention.
Tom's contempt is clearly displayed when he remarks, "I don't give big parties, you've got to make your house into a pigsty to have any friends..." an obvious reference to Gatsby's flamboyant parties.
His disgust is openly flaunted when he refers to Gatsby as "a common swindler" when they are in his apartment. He makes mention of Gatsby's association with Meyer Wolfshiem - a notorious underworld character, and he also refers to Gatsby's bootlegging and betting scams. His tirade against Gatsby has the necessary effect and Daisy clearly withdraws from Gatsby. She eventually tells him that he "wants too much." Tom, aware of this, then declares that Gatsby's "presumptuous little flirtation is over."
When Myrtle Wilson is later accidentally killed by Daisy, it is Tom who plants the idea in George Wilson's head that Gatsby was responsible and this ultimately leads to George killing Jay and then committing suicide.