I suspect that at least part of the problem here is that it is sometimes difficult to see - especially with an inherited document - exactly how formatting has been applied and consequently how it might be removed.
The problem is that _some_ formatting seems to get "stuck." This is either an implementation bug or, for some obscure reason, a design decision; which makes it a design bug.
Named styles are exclusive. Even though a style is _based_ on another style, recursively, applying a named style overrides the previous named style, whether the old style is an ancestor of the new style, or a completely different beast. That should be that as far as applying named styles goes. All that should be left is any "style fragments" that one has applied from the toolbar: bold, italic, etc; left, centered, etc; a particular font and so on. That may include bits of format applied through a format>paragraph or format>character menu, _provided_ that all of this formatting is removed by the 'Clear direct formatting' operation. _Everything_ else must be reset to the values defined (or defaulted) in the applied style.
This should not be a problem. If you like the look of some styling, create a new named style from the selection. Then extend and modify as required. That's what styles are all about.
The other thing is to clearly display the interaction of paragraph and list styles. The style name display should have the capacity to display ALL the named styles that are in play, and there should be a display option, similar to the 'Display special characters' button, to toggle 'Show direct formatting.'
It all boils down to being able to determine the source of any formatting, and being able, easily, to reset all formatting to a named style or set of complementary style types; paragraph, character, list.
And yes, your discussion does help.
Peter West
...he saw a poor widow put in two copper coins.