Dielectric materials like ceramic ferrules and composite MT ferrules are insulators, not conductors. Since they are not conductive, there is no place for any static to go. When static is created, the voltage remains trapped indefinitely on the device until a conductive path is created. Any debris residing inside the connector housing quickly becomes attracted to the ferrule end-face and can be tightly bonded to that surface.
Static charges on the end-face will attract and hold particulate debris for days and even months. The debris remains bonded to the end-face until the static charge finds a conductive path for it to dissipate.
The introduction of a cleaning fluid creates that conductive path, making it easy to physically wipe the debris away. The most effective cleaning process to solve this problem is using an optical grade cleaning fluid. The liquid temporarily creates the conductive medium for the static to dissipate.