I just had a session ruined in the following way.

1. I had an actor called "doppelganger assassin".
2. It was placed as a token with token name "commoner merchant"
3. A player cast polymorph on it and I used the transform activity to transform it into a crab.
4. The token name changed into "doppelganger assassin (Crab)" and the first roll spoiled the surprise in the chat.