To be fair, it's hard to polish a turd and there is no denying for a single, solitary second that The Last Knight was anything other than a turd.
So how do you mine it for material, then? Well, you don't. You simply point out just how awful it was and let it speak it for itself. The really amazing thing about this Honest Trailer is that you can almost tell how bored they are by Transformers. How do you keep hitting a punching bag like Honest Trailers before it becomes a hollow pursuit?
Who knows. Anyway, take a look and judge for yourself.