Why we sometimes say "not sure", and why that is the honest answer
Most label checkers force every product into yes or no. We keep a third answer, because the ingredient list often does not contain enough to decide.
29 Sept 2026 · 2 min read
Every product page on Skincare Check gives one of three answers: yes, no, or not sure. The third one surprises people. Here is exactly when we use it and why we would rather say it than guess.
Answer number one: the list is too short
Some products in the database have only a few ingredients on file, or a list that is clearly a fragment. We do not judge a product on three words. Below five ingredients the answer is not sure, and the page says so.
Answer number two: the list is not in INCI
INCI is the international naming standard for cosmetic ingredients, the Latin and English names you see on most packs. Some lists in the database were typed in French, Spanish or Portuguese instead. We translate the common terms, and we can still catch a paraben or a silicone in a French list, but we will not call a list clean when we cannot read every word of it.
Answer number three: the ingredient can come from two places
This is the big one for the vegan check. Glycerin can be made from plants or from animal fat. Stearic acid, cetearyl alcohol, glyceryl stearate, lecithin and squalane are the same story. The label uses one word for both origins. Unless the brand marks the product as vegan, the honest answer for those ingredients is not sure, and the page tells you which ingredient caused it.
Answer number four: the label and the list disagree
Sometimes the pack claims sulfate-free and the ingredient list on file shows Sodium Laureth Sulfate. One of the two is out of date: the brand may have reformulated, or the list was copied from an older pack. We do not pick a side. We show both facts and mark the product not sure, because a confident answer based on the wrong one would be worse than no answer.
What not sure is not
It is not a hidden no. When we find an animal-derived ingredient, a perfume, a paraben, a sulfate, a silicone or a drying alcohol, we say no and name it. Not sure means exactly what it says: the list on file does not settle the question. The fix is usually a better photo of the pack on Open Beauty Facts, and every product page links to it.
Why this matters
A checker that never says not sure is guessing some of the time, and you cannot tell which times. We would rather be right less often than be confidently wrong. If you have the product in hand, the label is the final word, and the page tells you which names to look for.