No, you have flawed logic ;) you're expecting logic from people.. ?
If you into a relationship expecting perfection, you will always be sadly mistaken as people are imperfect. Entering the relationship contract this way is "bad faith" but not unheard of.
I'm glad that you've never had to deal with it, but in reality it happens.
It presupposes that a person goes into a relationship looking for such an imperfection. This is the fallacy of affirming the consequent.