究竟BNO到神根國家是否要簽證?

It's true that holders of BNO passport doesn't require to obtain a Visa for entering any Schengen states, including Germany, for not more than 30 days since 19 January 2007. It's clearly stated on the websites of both British Consulate and German Consulate in Hong Kong. You may refer to the following announcement:
British Consulate: http://www.fco.gov.uk/servlet/Front?pagename=OpenMarket/Xcelerate/ShowPage&c=Page&cid=1123949999904
German Consulate: http://www.auswaertiges-amt.de/diplo/en/WillkommeninD/EinreiseUndAufenthalt/StaatenlisteVisumpflicht.html
In Europe, the immigration officers sometimes "forgot" that BNO is a visa-free passport for entering Schengen states. That's the reason we can hear your story and it is not a new thing already. Also, the BNO passports really looks like British Passport, some officers cannot distinguish the differences between two passports, so they refuse you to enter their country simply. Actually, they are protecting their country since real British can stay and work in Germany without limitation...
If you will use BNO to enter any Schengen states in the future, I advise you the print a copy of the list of BNO visa-free countries from the website of British Consulate. It will help you a lot !!