Examples of A.I. succeeding in non-obvious, and undesirable, ways
Some samples:
Evolved algorithm for landing aircraft exploited overflow errors in the physics simulator by creating large forces that were estimated to be zero, resulting in a perfect score
A robotic arm trained to slide a block to a target position on a table achieves the goal by moving the table itself.
Creatures bred for speed grow really tall and generate high velocities by falling over
AI trained to classify skin lesions as potentially cancerous learns that lesions photographed next to a ruler are more likely to be malignant.
And finally:
In an artificial life simulation where survival required energy but giving birth had no energy cost, one species evolved a sedentary lifestyle that consisted mostly of mating in order to produce new children which could be eaten (or used as mates to produce more edible children).