My thoughts… if I could run a quick update statement on the database that fixes it then I would, but I’d be very very careful and test this out beforehand (and make sure I’ve got backups)*
The ‘proper’ way would I imagine to write some custom code that uses web services to edit the content items in question and update the fields there, then check-in, transition, etc. etc.
just covering myself here for when tech support read this message
We have a similar situation where users had created hundreds of items with ‘font-size:x-small’ and other local formatting scattered everywhere, and then wanted us to fix things so that all of the pages displayed a consistent font size.
We put this in the page tempate instead of the Body field: