Influencing people - is it worth it?

I've recently read the book "Artful Persuasion" by Harry Mills (see the Amazon reviews).

All in all, it was an interesting book to read, it contains many fun anecdotes and quotes which entertain the reader and illustrate the point. Many of the suggestions should be fairly obvious to us, cynical consumers who are bombarded daily by advertisements. However, the most important question that I have, after reading the book, is: do I really want to do this?

One example which exemplifies my dilemma perfectly: the book recommends that, when trying to convince somebody, always use your credentials to establish credibility. However this flies in the face of my theory that "arguments should stand on their own, regardless of who presents them".

An other example: the book ends by describing seven methods for what it calls "mindless persuasion". In contrast my goal always is to have an intelligent discussion about topics focused around rational arguments.

I liked the tips about presentation methods, but the line is blurry there too. Should a presentation "win" just because it was more entertaining/fun? In the same time I believe in what I present (or what I'm arguing for), so isn't is my duty to use the best possible methods to convince people?

In the end, the positive thing that I've got from this book is that in the future I will recognize easier when someone tries to apply these methods to me, and maybe, but just maybe, I will use some of the things described there.