Some people are trained not to hear a difference. They have been told and so believe all cables sound the same, in all situations.
Only a person who carelessly ignored that claim's wording, could think that.
They are not trained to listen for noise in the chain or harmonic differences in sound. Our brain can easily ignore these cues. Others simply can't hear the difference due to the constant ringing/noise in their ears that they fight with each day. The definition of sound you hear may not be the same as your neighbor or your wife. I find it amazing in the rare case were everyone hears the same exact thing. It's quite rare except when the person is being told what they should hear before responding.
Do blind comparisons mean anything to you?