When soldering Micro-USB or USB-C connectors by hand, flux is applied generously. This sometimes results in flux getting inside the connector housing, making it sticky and creating high physical resistance when inserting and removing the cable. I have attempted using q-tips and small brushes with alcohol, but that does not seem to completely clean the housing. I also looked for compressed alcohol cans (similar to compressed air), but such a thing does not seem to exist.
What is a reliable way of cleaning this kind of connectors from flux residue?