I’ve noticed for quite some time that Google is placing tons of forums posts made on Vbulletin software into their supplemantal search index. Undoubtedly Vbulletin does create a lot of duplicate content, by default, but even on websites where they use robots.txt exclusions to limit Google’s crawling, the trouble is rampant.

I’m sure the things I’m noticing aren’t related to using VBulletin software. It’s just that forums tend to have a ton of interior pages, and many of those pages won’t have deeplinks to it. Even the internal linking structure of the website will make it tough to pass around much PR, so it’s understandable that as time goes on, more unimportant pages may go supplemental.

I’ve reviewed a number of sites where this has gone on for the past few months, and I haven’t seen the slightest improvement.