TT Scale. The Ideal Scale.

Well, there are different theories.
For shunting passenger trains the DB uses the class V60 (west, hopefully available soon from Kühn) with automatic couplers. These couplers are usually tilted upwards and fold down to couple. One dent theory is that these couplers cause the dents, when they are not completely horizontal before the V60 reaches the 101.
Another theory is an animal strike or - worse - a human accident.

Dibbedabb wrote: a human accident.

So since it's a "common" dent, 101s hit people on a regular basis?

Here in Germany we have around a thousand people using a train to commit suicide every year. Plus the people getting hit because they are to dumb or lazy to use a regular railway crossing. So, yes it's not so unusual, unfortunately.

Now back to something better.