I leave mine plugged in but I, most people here and I assume You unplug it at least fairly often just to move the amp, change instruments, etc. you'll never have an issue.
Where You can run into trouble (it's happened to me). If You have a rack system with amp, tuners, EQ's, BBE etc. we tend to leave these connecting patch cables in for long periods of time. I've definitely had oxidation problems. Some is attributed to moisture. Some is attributed to Galvanic corrosion. Galvanic Corrosion
All you have to do is basically exercise the jacks periodically and not let them sit too long.
Edit: pedal boards should be disassembled and all the cables and jacks whipped down periodically as well.
Where You can run into trouble (it's happened to me). If You have a rack system with amp, tuners, EQ's, BBE etc. we tend to leave these connecting patch cables in for long periods of time. I've definitely had oxidation problems. Some is attributed to moisture. Some is attributed to Galvanic corrosion. Galvanic Corrosion
All you have to do is basically exercise the jacks periodically and not let them sit too long.
Edit: pedal boards should be disassembled and all the cables and jacks whipped down periodically as well.