Someone who believes in cold-blooded mammals is either misusing the term “mammal” or the term “cold-blooded” or both, and I don’t think I’d refer to “cold-blooded mammals” without addressing the question of where that misunderstanding is. If people don’t understand you when you say “selfish” (because I think you are using an unpopular definition, if nothing else) why don’t you leave it out or try another word? If I was talking to someone who insisted that mammals were cold-blooded because they thought “warm” was synonymous with “water boils at this temperature” or something, I’d probably first try to correct them—which you seem to have attempted for “selfish” with mixed results—and then give up and switch to “endothermic”.
Someone who believes in cold-blooded mammals is either misusing the term “mammal” or the term “cold-blooded” or both, and I don’t think I’d refer to “cold-blooded mammals” without addressing the question of where that misunderstanding is. If people don’t understand you when you say “selfish” (because I think you are using an unpopular definition, if nothing else) why don’t you leave it out or try another word? If I was talking to someone who insisted that mammals were cold-blooded because they thought “warm” was synonymous with “water boils at this temperature” or something, I’d probably first try to correct them—which you seem to have attempted for “selfish” with mixed results—and then give up and switch to “endothermic”.
Sounds like good advice.