The things you will see over and over in forums...
 

Strawman - This is where you misrepresent your opponents position so that you can more easily destroy it.

For example -

Person A - I think that you should use hands controlled pivot.
Person B - This can't be true because the hands don't move the pivot.

This is a common arguement used to critique the golfing machine. However their arguement is completely fallacious and shows nothing but their inability to read 3 simple words, one of which includes the word 'controlled' which says nothing about 'moving' the pivot. They are refuting (or attempting to because sometimes they don't even do that) their own phantom arguement.

Ad Hominem - This is where you attack your opponents position by means of attacking your opponent.

Person A - I think the club should move on a plane
Person B - I've seen your swing on youtube and it sucks so therefore the club shouldn't move on a plane.

This is just two of the logical fallacies used over and over .... lets see if we can find some more...

Good examples! But even finding out more, is that possible to have mutual understanding? I try one:

Person A – I make good use of centrifugal force
Person B – Centrifugal force does not actually exist

Cliche Thinking:
using as evidence a well-known wise saying, as if that is proven, or as if it has no exceptions.

Damned if you do, damned if you don't...
 

Another technique that fortunately isn't used much here but have seen it a few times to be of note is where you ask a question where by answering you assume something already.

Person A - I think that xyz has a real function in the golf stroke.

Person B - Is it true that you no longer miss the ball 90% of the time?

Person A - Ummm yeah 'I suppose'.

Person B - Ha Ha, you used to be awful no wonder you had to resort to such silly measures to get better.