Something odd is definitely going on for you, but the URLs are formatted correctly and are going to subsequent pages correctly when I use FF or Chrome to visit ranches, showrooms, etc. I just checked out about a dozen different ones using Firefox and had no issues at all.
Unless this is happening in only specific showrooms/ranches/etc, and not every single one you go to, then I would guess that you probably need to update your version of Firefox. Something about the version you are using is reading the URL's incorrectly for whatever reason.
If it's happening only in specific ones, then there might be a problem with the name of the category in that user's shop - they may have used an odd character that is interfering somehow. If that is the case, let me know by llinking those shops here and I'll pass it on to be looked at by the coders.