How many are there? I just saw one I wasn't aware of: German Avenues Route.
These I've heard of/have been on/or just found: Alpen Strasse,Romantic Road,Fairytale Route,Castle Road,Wine Route,Ceramics Route,Baden Asparagus Route,Schleswig-Holstein Cheese Route,Motorbike Route,Lower Saxony Milk Route,Route of Industrial Heritage,Black Forest Spa Route,Glass Road,Framework Road,Fen Route,Ferries Route,Gemstone Route,Limes Route,Half-Timbered Houses Route,Clock Route,Toy Road,Green Route,Oxen Trail,Hohenzollern Route,Idyllic Route,Loreley and Castles Route,Lower Saxony Asparagus Route,Moselle Wine Route,Neckar-Alb Roman Route,Nibelung-Siegfried Route,Northern Black Forest Monasteries Route,Old Salt Road,Oranier Route,Osning Route,Romanesque Route,Saale-Unstrut Wine Route,Saxon Silver Mines Route,Sisi's Road,Swabian Alb Route,The Legendary Rhine-Romantic-Route,Via Claudia Augusta,Weser Marshes Route,Weser Renaissance Route. Anyone been on all of them?! I didn't realize there were so many. I guess you have to keep the tourists busy.

If the Romantik Road is included on any list of scenic routes it would cast doubt on all the routes being scenic IMO

Romantik Road, creation of the German Tourist Office in 60s or so - truck-filled two lane road with some nice, dreamy nice towns along it - but to me very unromatic and un-scenic.

I think I would call about 20% of those 'scenic'. No, haven't been to all of them, but I'd like to add another one 'Via Sacra' (In Saxony, leading into Czech Rep./Poland)

Oops, there is also a Saxon Wine Road. Btw, will drive the Saxon Silver Mines Road tomorrow ;-)

I should have set the subject as "German Tourist Routes"
That would be have been more accurate

Yes as even though some are not scenic, all can be delightful to drive...even though largely a creation of the German Tourist authorities to hype tourism your list is good to post.

the Route of Industrial Heritage for instance would attract me.

thanks for posting!