Hidden non-vegan things
It is not that easy sometimes, especially in the cosmetics world. For instance, if not otherwise declared, keratin treatment for your hair is made out of animal horns, hair, and hooves. If you don’t know, you don’t know.
The same goes for e. g. carmine, the bright red colour in cosmetics, alcoholic beverages, or candy, also known as E120. Carmine is extracted from scale insects’ shells, which irritates me anyway.
And these are just two examples. The list is way longer. I am just not aware of them all.