And much much more false negatives, which raises the question if the "stop eating this, this is bitter and bitter means poisonous" has any truth in it.
If bitter = poisonous, then the plants that evolve to be more bitter will be eaten less. Thus, non-poisonous foods that evolve to be more bitter have a genetic advantage over their less bitter counterparts.
That would be true if there were a fitness advantage for the plant when a herbivore dies, but in actually the fitness advantage comes from discouraging the herbivore from eating the plant.