Facing a Microsoft Word document that's filled with complex formatting? You can easily get it back to basics by using the Clear Formatting button, located top right in the Font section of the Home tab.
I had to explain this feature to a colleague recently, noting that it was much faster than his approach of selecting the entire document, pasting it into Notepad, and then pasting it back into Word. Because it's a relatively small icon on the ribbon with a non-obvious icon (an eraser with tiny letters above it), I suspect quite a few people miss it.
For an even quicker result, use the keyboard shortcut Control-Space. (For no obvious reason, the help text that shows up when you hover over the Clear Formatting button doesn't mention this shortcut.)