One particular strategy is the claim of "self" contradiction, when the contradiction is not between statements the opponent makes, but between some statements the opponent makes, and some statements that are deduced or inferred from what the opponent said and your own beliefs and concepts.

The fact that we are disagreeing is a strong indicator that there are contradictions between your priors and my priors and structural commitments on similar propositions, so that finding evidence of such contradictions is not really much of an indicator that you are wrong, let alone that you contradicted yourself.

Particularly when the claim of "self" contradiction comes from A critiquing B's theory without feedback or response from B, it's very easy for A to engage in a self congratulatory kabuki argument against B, then shutter his mind from further consideration of B's argument.