One thing people never think to question in the sandbox are custom winning criterions. When a challenge is posted with a poor winning criterion, such ashttps://codegolf.stackexchange.com/q/232974/100664, it can result in several problems, including the ability to get zero/infinitesimal score.
The problem with that one was that adding large amounts of characters to your program moved your score closer and closer to 1. I managed to fix it, but it would've been nice to think of in the first place.