I had the same experience as Anne-Marie. I had a paragraph style with All Caps as part of the style settings. I applied the style to a lowercase paragraph to turn it into all caps, with no local formatting or character style, i.e., no + sign next to the paragraph name.

But when I ran preptext.jsx (Mar 30, 2010 10:41 PM version), it decoupled the all caps relationship from the paragraph style, created a Caps character style and applied to it.

When I deleted the character style and replaced with none, and preserve formatting, the paragraph showed up as one with Text Overrides (local formatting) in Marc Autret’s ShowHideLocalFormatting.js and In-Tools’ ShowTextOverrides.jsx because now the attribute had been decoupled from the paragraph style, and the character style was deleted.

The so-called override attribute is exactly the same attribute in the paragraph style, and therefore, the + sign did not show up next to the name. To remove the “override,” I had to option-click on the paragraph style.

In a somewhat related matter, I tried PreserveLocalFormatting.jsx, but apparently it doesn't even work in CS 4: https://forums.adobe.com/thread/429756

Many scripts seem to be behind InDesign updates. I can't complain because they are free. But it would be great if script developers catch up soon.