Van der Vaart slammed the England international centre-back, who cost a world-record £80 million ($100m) when United signed him from Leicester City last summer, after he was nutmegged in the lead up to Bournemouth's opening goal in the Premier League clash last Saturday.
Maguire was left standing by Junior Stanislas, who then slammed the Cherries into a surprise lead at Old Trafford - although the home side came back to comfortably win 5-2 and keep up their challenge for the Champions League places.
The win was not enough to spare Maguire from stinging criticism, as former Netherlands international Van der Vaart accused the player of taking his club for a ride.
Speaking on Dutch TV station Ziggo, Van der Vaart said: "I think Maguire goes home every day and tells his wife: ‘I screw up, but I earn so much. They really believe I’m good.’ I really think so, he laughs at everyone."
It is not the first time van der Vaart has criticised Maguire on the same channel this season, saying his performance in the 1-1 draw with Liverpool last October was not worthy of a professional footballer.
He said: "If he is worth so much money, Virgil van Dijk is worth £300m. If I am going to play with the amateurs on Sunday afternoon, I can easily find three who can do this (what Maguire does on the pitch). I mean that seriously. A bit silly to say, but I really think so."
Van der Vaart went on to suggest that United manager Ole Gunnar Solskjaer should sign Bournemouth centre-back Nathan Ake as a replacement for Maguire.
Television cameras captured the United manager having a conversation with the Bournemouth defender at the final whistle, with some claiming he had said to the Dutchman that he needed a left-footed central defender.
Van der Vaart said: "That is nice if there is no crowd and no music after the game. Then you hear things like this. A transfer? I hope for him, I think he’s doing very well. Why not?"
However, Solskjaer subsequently dismissed the amateur lip-readers and said he has no intention of signing any more defenders this summer.
"I’ve got seven centre-backs, so I don’t know where that comes from. We’re fine," he said.