He was giving away a soap that was pretty good in cleaning a broad range of skin types.

Now he decided that freckled skin of redheads should be immediately dissolved on contact and didn't disclose it anywhere on the label.

Or, following on with your analogy - this is the blank ammo supplier for the film sets, but in the specific type of the weapons used on set the bullet explodes ripping off the fingers - but only from the latest release. Without any warning.