Obvious, but check to see if each works. Inspect the surrounds to insure they are intact (although it's not an advanced repair if not). Inspect the cones for any rips or tears- look close. If possible, remove the rear panel to insure the speakers are not replacements. If it's not removable, remove a woofer to look to see if it's original.
I picked up a pair of old Altecs last year. One had a blown voice coil, but I had already priced replacements and got a good deal on great speakers with an easy fix.
