I both agree and disagree with this sort of thing.

SEO "tricks" are crap.

On the other hand, using sensible markup to describe content correctly is not crap, and actually works.

Quick example: Often I see people using a series of DIV elements with some class for some common set of things. Like a sidebar, for example. This is bad mojo and should be avoided. Instead, use an unordered list. If you don't like that it gives you bullet points, you use CSS to turn them off.

Markup should be used as a means to describe the types of content it contains, CSS should be used to define the layout and look of that markup, and content-descriptive classes and id's should be used to connect the two. And yes, this will help your SEO value, tremendously. If you think Google doesn't pay attention to what is inside header and paragraph tags and such to assign relative importance values, then you're nuts.