Hi Randy, and thanks.
It's possible that the CSS could have munged the experiment, though I'm a bit skeptical.
The nofollow links were placed in h6 tags, which were styled in an external style sheet to have the same color as the background they were on. I tried to avoid some of the more obvious CSS tricks a search engine might pick up on, but it's possible they detected it by reading the CSS file and comparing the color of the text to the background-color of the div it was in.
Reading what I just wrote, I guess it doesn't seem that incredibly hard, but it seems like a lot of work to detect a few silly links, and might be giving the search engines too much credit. And there was no penalty handed down (not that there should have been, as I was just linking to a few articles on my own site).
I'm looking into some of those reports you mentioned about search engines detecting CSS tricks. I'm no advocate of shadowy haberdashery, but it seems like there's so many ways to structure a CSS file that detecting most of those tricks would take a huge amount of processing power. But perhaps not, if you've got the right algo.
For me, the hidden link was just because I wanted to test whether search engines were following nofollow links at all, and if the link was publicly viewable, someone else might have linked to that same page without nofollow.
At the time, nofollow wasn't being followed (at least in this trial). Of course, this is something search engines can turn off and on at will, so any testing really needs to be ongoing. I'll probably run the test again with a few modifications and see what turns up.
Taking a quick look at backlinks of some popular blogs that use nofollow, it does look like Yahoo is current showing nofollowed links in its backlinks, MSN is not, and, with Google, who can tell?
For example, a nofollow link on this page:
show up as a backlink here:
But just because a site shows up in a link: command, does that mean it's getting link pop? Not sure that's a question any of us here can answer.
<live links removed>
Edited by chrishirst, 16 November 2005 - 06:38 AM.