Modern Vespa

Neither. Look to applicable case law for a general idea of how this has been decided in the past. Doesn't necessarily mean it's always going to go that way. But that's where the odds are.

I know this thread is old but I wanted to add my two cents for anyone searching on the topic. My 17' Harley has a very similar issue in seeing the transmission oil after changing it. My long time indi mechanic taught me a trick that should work on these aftermarket dipsticks: Roll the dipstick over a clean portion of paper towel when you pull it out. This sill leave a clear mark on the towel that you can compare to the dipstick. Works like a charm!