If you search for a phrase which matches (fully or partially) the title of a post A, then the search results will contain every other post which the search engine recorded while post A was listed in the right panel.
In other words, the search engine recorder is picking up the right panel (latest titles, per forum) displayed while viewing other unrelated pages. So lots of other pages get inappropriately connected to all the keywords or phrases in those latest titles.
This results in a lot of unnecessary noise in the search results.
You can test it easily enough. Just search for a significant and uncommon portion of some title you currently see in the right panel`s Forum-latest lists. The search results will likely contain links (hits) to many unrelated pages. The incorrect assocation is made by the search engine because it reads those Forum titles as if they were part of the given hit pages.