Okay, let me explain very simply why this is incorrect.
Your inference is a very basic syllogism when ordered.
C: Slanderous attacks don't work because
P1: people don't reciprocate or enjoy negativity by in large
P2: if you have positive responses to them then it turns around on people like a mirror.
Before ordering we need to break things down. I'm not going to use symbolic logic because the forums don't support the characters.
C: Therefore (because), (slanderous attacks don't work) X
P1: Some (by in large) (people) S are ([those who] don't reciprocate or enjoy negativity) P
P2: If (you have positive responses to them)R then (it turns around on people like a mirror)M
Now that this is broken down we can order it correctly as such:
Some S are P
If R then M
Therefore, X
This is absolutely invalid. Furthermore, it is incoherent. While each premise is true (P2 is debatable but we will assume truth) the conclusion doesn't flow from the premises. Replace the variables with simple terms and you see what I mean.
Some dogs are animals
If this is a cat then it is a tabby
Therefore, dolphins can't walk.
Each premise is true but it doesn't support the conclusion. Even if we filled in the blanks with implied inferences it doesn't work.
Some people are those who do not enjoy negativity
Those who do not enjoy negativity are those who will respond to positive reactions
Thus, some people may respond to positive reactions
If stigma exists then slander cannot be nullified
If slander causes an unexpected positive reaction in people then it will render the slander impotent
Unexpected positive reactions render slander impotent
Therefore, if slander is nullified then stigma cannot exist
Here we have a fleshed out version that flows better. I'm not going to break this one down but it does.
While this flows nicely and is also valid it isn't sound. Why? Well, because you are stating that only "some" ("by in large") will follow this rule. You are admitting the possibility of an alternative response potentially exists. The only way you get this to work is if you state that all people are subject to this rule which is simply not the case.
Your reputation is actually how others view you. If someone can alter that perception to others then it can alter your reputation.
All S are P
All P are A
Therefore, all S are A
You can argue that your actions are what drive your reputation but if you do that then you're admitting that a reputation is indeed an outside view and therefore defeating your own argument. And that leaves you arguing a definition which you cannot win.
You may wonder why I took the time to do this. The reason is really simple: your argument is entirely absurd and stating it as fact is absolutely ridiculous (the math doesn't lie) and I believe that there is some responsibility to illustrate it as such when the topic is actually relevant and may have some import. This is the kind of idiotic reasoning that actually makes people dumber.