[zinekeller]

https://en.wikipedia.org/wiki/Generic_trademark

Xerox was eventually successful (at least in US), but there are cases like Bayer's Aspirin (surprise!) that were genericized.

[User23]

The Aspirin and Heroin trademark revocations were punitive and due to the war, not due to lack of proper defense.

That’s why you will see non-Bayer acetylsalicylic acid literally marketed as “Aspirin” but even though the Kleenex trademark is considerably weakened, you still don’t see competitors openly labeling their products with the name.

[bombcar]

Bayer didn’t seem all that concerned with defending Heroin™.