Exactly. Dust isn't good for any electronic device.
Posted via My Samsung Galaxy S6 Handheld Device
The only time dust becomes an issue is if it gets completely INSIDE a device and prevents the device from cooling, like in a laptop or PC. That's why you need to blow the dust out with compressed air. This does not happen with your headphone jack or microUSB port. I may hang out in those cavities, but it doesn't get inside the actual device.
I have NEVER covered ports on any of my phones, tablets, mp3 players (there are ports other than the headphone jack).
I have NEVER had a single issue related to dust.
I have ALWAYS plugged my devices in (at least nightly) to charge.
My current S3 (really looking forward to S6 upgrade soon!) is almost 3 years old, has never had ports covered, gets plugged in multiple times daily, lives in and out of my pocket constantly, and I've NEVER had an issue.
I'm fairly certain that dust DOES NOT conduct electricity, is NOT basic or acidic, does NOT spontaneously combust, and basically has no negative effects on the functionality of your device. If you look at some point and see some dust in there, just bend a paperclip and pull it out.
/rant (haha, sorry it was so ranty)