inside aebrahim’s head

I just noticed that Firefox is the featured article on Wikipedia. It’s been like that for a few days now (according to the page history), but I thought I’d point it out anyway.

I have a question for webmasters out there who have some experience with SEO. How does Google treat the following?

a) Text that has class=”foo” where class foo is undefined.
b) HTML comments (including IE’s conditional comments).

My expectation is that it that for (a), class foo will be ignored entirely (no loss or gain in terms of SEO), and that HTML comments (including conditional comments) are also ignored entirely.

Does anyone have evidence to the contrary? Maybe some Mozilla folks out there know about this. I’m not worried about this for my blog, but another site that is considering advertising Firefox in place of some normal header text. For them, even marginal loss in terms of SEO may place it below another competing site (which would be unacceptable). Thanks in advance for your input.