This happens to me as well, to the point I nearly tried to get a refund for the pack - it breaks the character of the Sim at higher levels. At celebrity level 3, it happens a bit but is generally reasonable. The problems start at celebrity level 4, it feels like the game nearly robs control of your sim as they wallow in their repugnant self-absorption. In a recent new save after getting level 4 fame, the character probably reacted in disgust to almost every new sim who came in to the bar. This is compounded by how notoriously difficult it is to de-queue this action after spotting it. It refuses to clear it then forces the action through practically every time.
I feel like this level of disgust with the unwashed masses should be a trait or quirk that can be chosen, as I would hazard a guess that not everyone wants any sim who becomes famous to become an absolutely terrible person who even scoffs at the sight of their boyfriend/girlfriend. Does a sim really need to marry someone before they stop viewing them as dirt beneath their heel for not being equally famous? Then again, that's just personal opinion/input and not really a bug report. The bug does compound the loss of control though, both control over gameplay and control over who the sim seems to become as a person.
Also, as the OP mentioned, this can easily happen with the same person on the same lot, so long as they've left the immediate area and come back later, such as using the restroom or going to another floor. Apparently object permanence is a trifle that the truly famous cannot be bothered with.
