I got an estimate at a body shop for a dent years ago. The owner of the shop said at one point “Of course they’ll try to jew you down on the price.” I went mildly still and met his eyes, a social cue he picked up immediately. He looked away and fumbled awkwardly “Although maybe I could have found a better way to put that.”
Yes, he could have said gyp, because the derivation from “Gypsy” is no longer noticed. The word entered English before we became sensitized to ethnic slurs, and had already been disguised by shortening, unlike indian giver. When I was a child, “Chinese” was a descriptor for anything that seemed topsy-turvy or unexplainable, as in chinese fire drill. This was probably a combination of stereotypes: China was the other side of the world, where you would end up if you dug straight down, so it seemed likely that they would do things backwards or inside–out there. They also looked different, and so just about anything about them seemed believable. Anything about anyone who was different seemed possible. Heck, we believed that people from Massachusetts were capable of strange things, and it turned out we were right. And in Connecticut there were New Englanders who rooted for the Yankees, so all bets were off once you got south of Nashua.
Most people in that era who used some insensitive ethnic accusations did so without necessarily thinking about Jews, Indians, Chinese, or certainly Gypsies. People don't think much at all. I imagine it had an effect on how they viewed each group without realizing where the stereotype had come from. I don't doubt that the connection became conscious from time to time and even extended prejudices. But words of insult generally lose their power over time. Taboos are strange things, and sometimes the insult will intensify, but this is rare.
To call someone a "Red" became so overused that it became humorous. As communism recedes from the face of the earth (faster, please), the insult will likely erode into an archaism in a few generations, as "know-nothing" or "bimetallism" are now.
I have been reading the warning for years that the term Nazi, and the related fascist, brownshirt, etc. would become watered-down and meaningless by overapplication. That is already occurring. Could someone have been humorously called a "soup nazi" in the 1950's or 60's? While it still has considerable power to insult in my generation, the next generation has less to base the understanding on. Knowing about Nazis and WWII was in the air when I was growing up, from all those war movies to "Hogan's Heroes." Unless a student is more knowledgeable than average about 20th C history, or religious history, or military history, I think the word Nazi has become more vague. Like cossack, or even vandal, the association with real events is being lost. Fascist has come to mean little more than "bad, with elements of control and militarism." In 50 years it will mean just "bad," and sixth-graders will do school reports on where the word comes from.