Although she is generally dimwitted, high, or drunk (often all at once), Victoria is much more intelligent than other characters give her credit for.
When Peggy got into a fight with Mike and announced that she would not attend his wedding because Mike was inviting his father, it was Victoria that convinced her to reconsider by pointing out how well Mike turned out because of Peggy's influence.
He lives with his grandma until the middle of Season 3, as he has not been able or motivated to find his own place.
Until the middle of Season 2, he did not have a steady girlfriend, and Mike has frequently alluded to Carl employing prostitutes or having one-night stands with strippers.
Carl then gets angry with Victoria when she is relieved that he didn't propose, and that leads to a spiral in the Season 5 finale where he has broken up with her.