Det er litt sannhet i det du sier, fra Erowid:
"The standard identifying mark of most Psilocybes is that they stain blue when touched or cut; unless specifically noted otherwise, assume all mushrooms listed here do. Mind you, this blueing alone is not sufficient for identification as a non-poisonous and hallucinogenic mushroom!"

Det betyr enkelt og greit at ja, de fleste psilocybe soppene blir blå, men ikke la identifiseringa hvile på det alene.