During victory over Bournemouth on Saturday, Maguire was nutmegged by Junior Stanislas before the winger darted beyond the England international and rifled a shot past David de Gea at the goalkeeper's near post.
When asked about Maguire's error on Ziggo Sport, Van der Vaart said: "I think Maguire goes home every day and tells his wife: 'I'm so s*** at football, but I earn so much. They really believe I'm good'.
"I really think so, he laughs at everyone."
Earlier this season, Van der Vaart also took aim at the England defender.
"He can do something, but if he is worth so much money, Virgil van Dijk is worth £300million," Van der Vaart explained.
"If I am going to play with the amateurs on Sunday afternoon, I can easily find three who can do this. I mean that seriously. A bit silly to say, but I really think so."