@Walt - there is an obvious answer
. This plugin strips periods from titles. This is because when I first wrote this plugin nearly a year ago I found there were a number of the initial set of websites that choked on them. Note that metadata download searches strip periods as well. When the plugin was first written it did not use the template processor, so I took the decision to hard-code and strip them always.
The downside of this decision is that if you hit a website with a really crappy search engine (like FictionDB) which is relying on exact matching, you won't get a match.
Now in theory I could go back through every other URL in the plugin and put in template expressions like {title:re(\.,)} and {author:re(\., )} and remove my "always strip" code. However unless I write special migration code that won't be picked up by every user of the plugin out there and it complicates all the urls.
As you say it is only a small % of books that will hit this problem on a small % of the websites it supports. If it is a big problem for people I guess I can revisit it. Personally in my daily usage it has never been a problem in its current guise, but then I don't use FictionDB. And I just accept that once in a blue moon the title I have in Calibre is not close enough to what a website has, and either re-search by author/ISBN or just manually on the website page that is opened.