I took a long weekend to visit my family up in Massachusetts this weekend, and decided to pull out my old vintage Macs tonight. They have been in my parents' basement (with a dehumidifier, they have never gotten wet) for the past six years or so. I achieved the following results.

512K: will not boot, screen displays a white line and the system constantly tries to eject a disk even when nothing is in the drive.

Plus (beige): boots fine, 100% functional

LC w/13" monitor: boots fine, 100% functional

LCII w/13" monitor: boots fine, 100% functional

Performa 575: 100% functional

For having been stored this long, I'm happy with this result. I'm going to tinker with the 512 a bit to see if I can get it to function.