Let's see...
Mac Plus: new power supply @ age 6, otherwise no problems
Performa 578: no problems over 5 years
PowerMac 7500/100: some software issues, but no hardware problems
iMac G3/500: dead hard drive @ age 3, otherwise no problems
iBook G3/900: Dead power adapter. Dead logic board and hard drive. Dead logic board. Dead logic board. Dead logic board, replacement issued.
iBook G4/1.2: video cut out. Video cut out (likely a video cable issue; video cable was replaced after the second time it happened, so I'm hoping it holds up for a while).
Brother's iBook G4/1.0: dead hard drive.
iMac G3/233: blown video card @ age 6.5, otherwise no problems.
Sister's PowerBook G4/1.5 15": no issues.
Sister's PowerMac G4/733: no issues, aside from the power supply or something (PMU?) needing to be reset after a power outage.
I can understand the dead hard drives, being that Apple doesn't make them. As for the rest, well, I haven't had much luck with my iBooks.