I honestly don't see that many labelled incorrectly. Sure there are the odd few. But the Part Time isn't a rare or collectable style (there are some more desirable colours with all styles). Visually one way of telling the PT apart from the City (aside from size which isn't always easy to tell in pics) is that it has a vertical seam running down the centre of the bag. The City doesn't.but sometimes the best deals are from sellers who aren't getting name right, don't know color name, season, etc?
Of course I'm not that savvy myself but others here (like you) are
Takes more patience to search all Bal instead of just the part time, etc but might find a deal that's labelled incorrectly