Bad - baby does humongous leaky poo just as you are about to leave the house and already late.
Accidentally shutting toddler's fingers in a door.
Anything resulting in a visit to A&E. ("Go directly to A&E. Do not pass Go. Do not collect £200"
)
Ominous silences from the next room.
Repeated night wake-ups (teething, covers fallen off, comforter lost, need wee-wee, "just making sure you are there mummy", ....)
Child copies you swearing after one of the above incidents.
Good - children manage to play together/separately for 10 whole minutes without anyone hitting anyone, crying, breaking anything or falling over.
When you sneak into their bedrooms and they are fast asleep looking all angelic and smelling lovely.
Strangers complimenting you unexpectedly on their behaviour.
Rare/unexpected compliments from the children (of the "you are a lovely mummy" variety).
Snuggling.