I am going to cheat and give a second answer. In reality, it is very difficult to know the intentions of others. You can say someone's work is well done, convincing, or the opposites of those things. What is a general word for the opposites of those things? We all tend to use words like myth, legend, etc in genealogy (not to mention imposture) but in the light of day what we mean in practice is that there is a popular narrative which is "wrong".
Deliberately wrong? Normally impossible to tell, and in any case see the concept of "Doublethink". Humans mislead themselves. The two key properties are "wrong" and "popular" (or some other description of how well-known and widely-believed it is).