Why did Daisy and Tom find Gatsby's party loathsome in "The Great Gatsby"?
Why does Gatsby get so many phone calls? What does this say about him?
Consider this quote from Chapter 6:
But the rest offended her—and inarguably, because it wasn’t a gesture but an emotion. She was appalled by West Egg, this unprecedented “place.” that Broadway had begotten upon a Long Island fishing village—appalled by its raw vigor that chafed under the old euphemisms and by the too obtrusive fate that herded its inhabitants along a short-cut from nothing to nothing. She saw something awful in the very simplicity she failed to understand.
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 - so much.
Daisy and Tom found Gatsby's party as loathsome because the attendees of the party did not act like them. Daisy and Tom have a reputation to uphold and therefore act more sophisticated that the rest of the attendees. They are more uptight, and not as loose and open as the party members. The party members were not to their 'standards' or not someone that can essentially talk to.
Daisy and Tom look down on anyone who are not apart of their social circle. Unless they have money that has been passed down throughout the generations Daisy and Tom will not gives these people the time of day. The reason they find it so insulting is that first these put are not up to their level, secondly these people do not act as if they have money by the way they are so openly and flagrant. Which is why Daisy might have said that these people may have snuck into the event.