What is a characteristic of gentian violet?

Gentian violet is known for its distinct purple color, which makes it a permanent stain on fabrics and other materials. This characteristic is significant in clinical and laboratory settings, as it requires careful handling to prevent unwanted stains on clothing or surfaces. The staining property is due to its chemical composition and ability to adhere to various surfaces.

While gentian violet does have applications as a topical antiseptic for certain types of infections, particularly fungal infections like oral thrush, that context does not negate its notorious staining ability. It is not effective against viral infections, which helps to differentiate its use from other treatments. Although gentian violet can have side effects, particularly allergic reactions in some individuals, saying it has no adverse effects isn't accurate given the potential for irritation or allergic responses. Therefore, the option highlighting its property to stain permanently is the most characteristic and noteworthy aspect of gentian violet.