[old_tv_nut]

Many old electrolytics with unspecifed tolerance were in filter circuits where the main requrement was a minimum capacitance, so tolerance if unspecified was something like -20% and +50% (or more). This reduced the cost because anything that came off the capacitor maker's line was acceptable.

It is theoretically possible to overstress the rectifier that drives these capacitors if they are too large (causing a large peak charging current), but usually the rectifiers are spec'd to allow a huge + tolerance on the capacitor size.