Thanks for all the replies.

This is basically what we (try to) do. The problem is these documents are hundreds of pages, hundreds of paragraphs so it's not feasible to click individual paragraphs. If they were authored 'properly', we could do 'select with similar formatting', but they aren't, so can't

I agree that all the manual changes (line spacing, font etc.) are a part of the problem. We have no control over the authoring of them so just need the shortest path to fix them. It probably gets updated by 2 or 3 different places before we see it.

Another update: our non-heading style is set to 'at least 22pt' line spacing. This is the problem. Well it's not a problem in a 'clean' document, but the ones we get in it is causing the 'extra' spacing. If I change it to 'exactly 22pt' it looks exactly like a clean one set that is set to 'at least'. The problem here is that we sometimes have inline images that can be taller than 22pt, so they get clipped when set to 'exactly'. That is what we went with 'at least'.

I don't think there's a simple solution.