I have the same question as you, and I found this link helpful.
http://www.anatekcorp.com/testequipment/esrcompar.htm
It appears that having an ESR meter is not a cure all, or substitute for replaceing your electrolytics. The opinion of some members here is that even if it tests good now, eventually it will cause you a problem. I guess that is just the nature of the beast. Old dryed out electrolytics days are numbered, so you might as well just replace them, even if it is a pain in the ass. I hate doing it and I guess we all do, but after puting all the hard work into restorting an old set, whats another 2 hours per can to restuff them.
First thing I do when I start out restoring a chassis is to order fresh electrolytics. Once I have them on hand, I don't have any excuse for not re-stuffing the cans. After all, I already spent the money, why just let the caps sit there collecting dust. Might as well put them to work. I think the temptation for all of us is to try and get away with as little work as possible.
I read a post yeaterday and someone said that burning out a transformer due to a shorted can cured him of using the old cans. Now he replaces all of them as standard practice. I think that is good advice, even if it's a lot more work.