3. It must be deceptive

When I previously asked a question relating to the straw man fallacy you pointed out an interesting distinction that:

3. It must be deceptive in that it often fools the average adult.

Now on reflection almost every example of people crying straw man over the years is actually just a lack of attention, skim reading, etc. (or in my case I think I may have dyslexia and sometimes I read something over again and notice it said the complete opposite of what I thought I'd read), not understanding what was said. or maybe just an error in paraphrasing.

I'm now in the position that I'm tending towards people not being deceptive, but I'm wondering, when is there ever a time where you can be sure that someone is being deceptive? I think that's a bold claim to make against anyone.

Consider that there are two aspects of "deceptive." One, is the intent to deceive and the other is being deceived . The question is, can someone unintentionally deceive another? I think one could... subconsciously or through habit. A secondary definition of "deception" allows for a thing to deceive, meaning that the way an argument is phrased can be deceptive, even if no deliberate or subconscious act of deception is taking place by the arguer.

The reason for rule #3 is because without it, far too many non-fallacies would qualify as a fallacy.