I don't think it's actually possible to shut it off, any more than we can stop seeing what people are wearing, hear what they are saying, what their expressions are. For me, to not look is rather like suggesting we should shut our eyes when we talk to someone. What we do with what we are aware of is something else again and I agree very much with what
@Kgal said. Just because someone has a strange taste in fashion doesn't mean we should comment on it but we still notice it - it's the same with how people behave. It will however colour how I respond to people below the surface.