No excuse. Know the aircraft that you're going to be using for a checkride. It's not like there was a possibility of 25 different aircraft, and on the day you show up, is the day you find out which one it is and you'd better know it! Cease Quibbling.
Like has been alluded to, yes, it's a teaching test. But you have to know the knowledge in order to teach it. And you can't rely solely on notes or cheats to do it. Some things you just have to know.
Again, some things you have to just know. Not everything is a "classroom". If you have to explain something about airspace while in the air and in the cockpit for some reason, you're not going to have your dry erase board and book of diagrams.
Learn some freaking flexibility and how to make do with the cards you're dealt at any given moment.

Not everything is black and white there junior.
Christ......kids of today want every damn thing handed to them on a silver freaking platter.
Seriously....not knowing how many cylinders a 172 engine has? It's not like you were being asked what the spark plug gap was for each cylinder, or being taken to a hangar where there was an O-360 in pieces and you were told to assemble it and get it running in 10 minutes. And it's not like the 172 has an R-4360 engine with 28 cylinders in 4 rows.
Being asked how many cylinders the engine has, is like being asked how many tires are on a 172. Seriously.
So knock off the candyass excuses, the incessant whining and quibbling, the passing of the buck for stuff that
you should've known, look up the term "flexibility" in the dictionary and learn how to teach without needing every damn crutch known to man 24/7, hit the books and take it again. It's up to you and only you whether you screw it away again or not.