I think it is because you are not used to it or because maybe you do not like it. The more you wear/smell a scent the better you become at dissecting all the differences and individual characteristics of the same scent.
On the other hand, you may not like the powdery (florals and oak moss notes) notes of classic perfumes. I cannot stand Nutmeg on my skin. When someone else wears it, it smells OK, but when it touches my skin it just grows and grows and gross. Ew.