Connotations/euphemisms get discussed in moral psychology, often under the headings moral disengagement, dehumanization, and construal. One example I recall hearing is that people would be more willing to cheat on a test if it's thought of as "peeking at my neighbor's paper" (although searching for this, it looks like it's not from a study, just a hypothetical example in a Trope & Lieberman article%20Temporal%20Construal.pdf)).
What I've seen of the moral disengagement literature mostly involves theorizing and correlational studies using personality measures, rather than experimental studies (e.g. Bandura et al., 1996). I did come across one experimental study on dehumanization, which finds that people give more electric shock to other people who have been called "animals" (described here), although it's not a very well-controlled study.
There's plenty of experimental work about how humans make poor judgments and decisions, but I haven't yet found much about how humans make poor judgments and decisions because of confusions about words. And yet, I expect such errors are common — I, at least, encounter them frequently.
It would be nice to have some scientific studies which illustrate the ways in which confusions about words affect everyday decision making, but instead all I can do is make philosophical arguments and point people to things like Yudkowsky's 37 Ways That Words Can Be Wrong or Chalmers' Verbal Disputes and Philosophical Progress.
Which keywords do I need to find experimental work on this topic? I tried Google scholar searches like "fuzzy concepts" "decision making" and effect of connotations on choices but I didn't find much in my first hour of looking into this.