In using a few different plugins recently, I have had issues with custom taxonomy links returning all posts instead of just those that have been tagged with that specific tag. So for instance, when you click on the custom tag "Belgium," you get all posts, even those that aren't tagged "Belgium."
Here's a page that shows the results. If you click on any of the three country tags on the left side, you get the same thing--all posts. Each one should only have one post tagged with that country.
These tags were made with the Custom Taxonomy plugin, but I also had issues with the Country Post plugin--so I think the problem is with my scripting, not the plugins.
At this point, this is only happening with the custom taxonomy, not the built in tag or category--those work fine.
I am using a child theme I designed based on TwentyEleven.