Why did daisy and tom find gatsby's party loathesome?

Daisy and Tom are old money. They like status and reputation. The people gathered at Gatsby's house are no particularly well known (except for a few), and they behave openly in a manner that was not traditionally accepted. Tom asks Nick, "Did you notice Daisy’s face when that girl asked her to put her under a cold shower?” He is implying that Daisy was offended by the behavior that would cause a woman to get drunk enough at a party to ask such a request of a stranger. Daisy tries to defend Gatsby, and the party, by saying that many people come who are not invited, suggesting that it is only these people who behave so badly. It is the "commonness" and the freedom of the gathering that offends them - and their rigid social expectations