Days after Tesla CEO Elon Musk purchased social media giant Twitter, the coveted blue check mark signaling an accountholder’s verified identity went up for sale at $8 a pop, an initiative called Twitter Blue.

A click on the check mark notifies whether it’s an “earned” badge owing to a user’s public official status, or if it is purchased. However, as insulin maker Eli Lilly quickly found out, not many users investigate whether an account is legitimate.