This is an interesting one and I’m going entirely off anecdotal evidence here: yes, you will be seeing David Hasselhoff posters and the like quite often throughout Germany. Me personally, I have yet to meet a single person who unironically likes his music or is a „fan“ (whatever that may mean to you) - and this holds true for the generation of my parents as well.
My working theory is that there’s some kind of reverse self-fulfilling prophecy at play here: It’s been imposed on Germans that “we love Hasselhoff” over and over again and at some point we just went with it, albeit it’s mostly and irony thing now.
Then again, I might be totally off and not realize that I’m looking at it from within a bubble of people not actually liking him.