What I find most frustrating are the bills written as prose-diffs themselves: "In some entirely different piece of law, Foo shall be inserted after Bar, with an overall effect and purpose which will not be described here."
One of my friends is a public health lobbyist and she is used to having to explain to stakeholders that THIS formatting mark in the PDF means they're adding text but THAT formatting mark means they're deleting text. It's not immediately obvious and every state has its own way of presenting information. I'd argue that DC does it best, but I haven't looked at every legislature.