derogation

If I were to assassinate a person’s character, that would be derogation – by my derogatory comments I am spoiling their reputation.

If I were to say, purely by way of example, that the directors of a company that manufactured a car like, just for example, a Morgan were hopelessly incompetent by allowing production to continue when they KNEW that their vehicles could not pass vehicle emission tests …… if I were to say that and if there was not even a grain of justification in my claim, that would be derogatory. In fact, to the best of my knowledge, there is no justification for that statement and I just wish that I could afford one of the Morgan cars

But I’m sure that there must be all sorts of “strange” activities going on in the world of motor manufacturing

That’s derogatory – openly questionning a person’s competence, ability, intelligence without going so far that it could be classed as slander / libel in a court of law