Mauricio is dumping a genetically flawless woman because of one miniscule difference on something as unimportant as her feet.
Hal spends his entire life trying to live up to his fathers shallow standards. He lives his every day life the way his father told him to when he was a young boy. When he meets Jill, his neighbor, he finds her to be stunningly beautiful, so Hal decides to go in for the kill and ask her out on a date. Her response to Hal's out-of-the-blue question is, "I said no, I don"t want to get a drink with you, I want to go home. Hal, I"m not attracted to you." Then she adds, "You are going to be so busy with your new promotion that you won"t even have time to think about me." Hal says, "How can I not think about you, you live right across the hall from me." And Jill's final comment before walking away from Hal is, "I don"t know Hal, maybe you should think about moving." This is extremely shallow of Jill because she won"t even take the time to get to know Hal as a person; she already has her mind made up about the date just by judging Hal's appearance.
In the next scene we observe Mauricio being very shallow again. He and Hal are at the bar, and Walt, who has spine abifida, shows up. Mauricio sees Walt trying to impress the lady's with his arm strength and Mauricio comments, "Awww shit. He's here." Hal says, "You have a problem with Walt?" Mauricio says, "You don"t? Don"t you just get sick of it sometimes? The whole I walk on all fours so I own the world thing!" Hal says, "He's just playing the hand he was dealt!" And at that moment Walt decides to join Hal and Mauricio and Mauricio says, "Ohhh, here he comes!" This is shallow of Mauricio because he dislikes Walt for being able to get the ladies by using his disability to his advantage. Some of this is brought upon by jealousy, but a lot of it is just the fact that Walt isn"t "normal" so Mauricio looks down on him.