I don't like the Matty shown by the OP at all. The one below is from an original owner's grandkid, which I got raw in 1997 as my first ever T206 card. The top is a little thin, but the fat bottom border makes up for the difference.
Other than obviously perceptible scissor/wavy cuts (which can leave the corners with so-called "bat ears"), the best way to tell whether a T206 card is trimmed requires taking the card out of the holder -- you have to look directly at the edges and compare all four with each other. On trimmed T206 cards, you will see a cleaner and whiter border, while two or three other edges will be a bit browner, and you can actually see the diagonal striations from the original factory cut. Also, a factory cut T206 edge will not have sharp right angle front surface-to-edge and then edge-to-back surface. It will be slightly soft or rounded.
These methods were written about in SGC Collector magazine maybe 8-10 years ago, and it has worked for me since. Practice on one that you know is trimmed and you start to understand the process of spotting trimmed cards a lot better.