Example of pt #1 in above post: Let’s say I am trying to find out about a guy name Shmuely. I ask Dovid how smart he is. He tells me that he has an iq of 120. That is very different than if he would tell me that he is less intelligent than Reuven even if I already knew that Reuven’s iq is 130 so I could have figured it out myself.
By specifically pointing out that Shmuely’s iq is lower than Reuven’s, he has now made me think negatively of Shmuely and made me think I should go out with Reuven instead. (and just for the record, I have never asked for anyone’s iq – I was just trying to think of an objective fact that can be used to describe someone).
Another point that just occurred to me: If you make the point of saying that someone’s iq is less than someone else’s, you are implying that the difference is significant. If the price of milk in one place is $1.50 and in another place is $1.55 and you say that in place B it is more expensive than it is in place A, it is not simply an objective statement – you have now made it sound like the difference is significant. (and it actually may be irrelevant compared to the extra money you have to spend on gas to get to A).