Yes totally agree re cleaning up and redoing some of old listings.

Have been doing exactly the same to re-birth ours.

We have quite a lot that are fairly old and so have been slowly going through and tweeking and rejigging.

As you say bulk editing doesn't work, have to open each one to see just how it actually looks, and reads.

Have found a couple of doozies that had slipped through so well worth it.

But once cleaned up and re-listed have found some are selling so just proves that there are a lot of new lookers and buyers around and is well worth it. 

Have a go, just do a few every day and good luck.