Terms like dumb are ableist in origin, but most of the time I feel like they have become so idiomatic that they are almost entirely divorced from that origin.

But then I have to consider that I am a straight, white, able-bodied, middle class male living in the imperial core, practically privilege personified, and I have heard bigots use the idiomatic argument to justify saying the n-word or removed or whatever. So now I still use them, but after I do I stop to consider whether or not it was wrong to do so and hope someone else will figure it out for me.