Could there be a degree of "sour grapes" here resulting from finding one's self inexplicably unpersuasive next to a velvet tongued dummy?

I tend to be quite persuasive. I'm sure I'll find something else to be resentful about.

Are we sure we eschew the tactics of rhetoric because they're wrong? Is it even fair to describe "dark arts" as wrong?

'Wrong'? Describing things as 'wrong' is a dark art.