Delete all in Catalog settings

[Octopuss]

...doesn't work at all. You have to click on each line and individually delete it.

[xnview]

you can select more than 1 line to delete entries.

but you're right, 'delete' and 'delete all' have not the same behavior. 'Delete' remove the entry and all datas. 'Delete all' remove the entries only if no category/rating is assigned

[Erixx haxx]

"Delete Unused" or "Cleanup" sounds like better words to me. Or have a tooltip.
I doubt new ppl would know what this does. If I see "Delete All" I would never press it..