How long should a clutch last on a 2005 Kia Spectra and how do you know if its going bad?

Properly operated the clutch should last at least three or five years of normal driving without servicing being necessary. If a driver often "rides" the clutch, that is keeps his foot on it, then the main clutch bearing will deteriorate faster. When it becomes difficult to engage the clutch and change gears, for example it does not disengage until you step on it all the way to the floor, then the clutch should be inspected and the parts replaced as necessary.