If you're looking for samples you'll probably find sufficient if you're looking for NPD affiliates (they're not illegal either). If you look up cases where the affiliation is left-wing or anarchist you'll find even more. The standards for teachers are really very strict [1] - the must be "weltanschaulich neutral".
There's certainly a debate to be had about whether they're too strict, but IMHO, Höcke is so far across the line that I'm all in favor of keeping him out.
Edit: Note: higher standards apply for all government employees, but they're stricter for some, among them teachers, police etc.
When I started working in public sector I had to sign that I'm not a member of an unconstitutional group. As examples it included a list similar to this one: https://www.justiz.bayern.de/media/pdf/verzeichnis_extrorgan... It includes left-wing, right-wing, and islamist extremist groups.
Interestingly this list also contains the leftist party "Die Linke" which now has been a member of the federal parliament for a rather long time. That being said it's probably not a hindrance if you are a member there but you are expected to explain yourself.
Die Linke is seen by some as some sort of pariah in the German political landscape, due to its legacy and roots in the SED from which they never really distanced themselves in a very clear form. It's a bit of a touchy topic and the expansion to west Germany swept up a lot of nutcases, some of them in the more extremist spectrum. The topic gets even more confused since they're fairly well rooted in Eastern Germany where they are basically a left wing form of the SPD while they never managed to achieve that success in the West.
There's certainly a debate to be had about whether they're too strict, but IMHO, Höcke is so far across the line that I'm all in favor of keeping him out.
Edit: Note: higher standards apply for all government employees, but they're stricter for some, among them teachers, police etc.