Oreos are a famous (and my favourite) example :)
Among those that herbivores would like to convert, "vegan" is saddled with negative perceptions.
As someone who's trying to follow a vegan diet I am very happy about "plant-based" food generally being vegan though!
If we're talking about shoes, or cars, then the euphemism will be something like "cruelty-free". No car company is going to associate their cloth interiors with veganism. Well, maybe Subaru would :)
If you are gluten free because you can't tolerate gluten, that labeling is very helpful.
As someone who is gluten free because I can't tolerate gluten, I would add that, for those who don't have that issue, gluten free food is not always the healthiest choice. In particular, gluten free baking is tricky, and gluten free baked goods are generally much higher in sugar.