Basically he said you can use any fluid that dries up quickly to clean the USB port like acetone, thinners etc. This is actually a bad idea as acetone for example can dissol certain plastics. The better way is to use known safe cleaning liquids on your device like isopropyl alchol or contact cleaner or compressed air that you can buy in a can depending on where you live these might be easily available or not. Thenake sure the device is off and if the battery can be removed please remove to to avoid electrical problems. Then you can used a small cottom swab to clean inside the US port, but first you can spray with the previous mentioned stuff like isopropyl alchol so it can loosed the dirt. After you can cleaned out most of the dirt, inspect as best you can inside the port. Use a flashlight if possible so you can see the individual pins of the port. USB ports have 4 pins and they all need to be connecting for a USB device to work so make sure the ponds inside the port are springy and they are all a uniform height and also compare with other USB ports to see if the height of the pins are OK. If not you can use a paperclip or some other small tool to gently raise the pinds higher until they look OK..
