There's no truth one can speak of which is inherently degrading. It's all about intent. Since no characteristic is universal to any group, making a universal declaration is not truthful. Making a general observation, otoh, certainly can be.
This reminds me of one hysteric who claimed I was a bigot for observing (and my observation was appropriate in the context of the conversation) that people of primarily Scandinavian descent are, on average, taller than people of primarily Italian descent.
Even after I gave him proof of it, he still screamed that it wasn't true, that it was just bigotry.
Factual truth is what it is. Accusations of any kind of bigotry should not be used to silence it.
If any person has evidence that the telling of it is intended for the sole purpose of being demeaning, that's another matter. That person would naturally be required to substatiate that.