I have to say though, when you are a german couple, have a double income with no children/no pets, its not that hard to find something. I don't envy the rest though!
We've been doing it for many years and have tried many things, but if anyone has further suggestions always happy to learn.
In cities like Munich, speed is very important - is your search real-time or at least near rt? If so, I'd advertise that. I need to be sure I'm not missing any offerings, and that they aren't slower to show than when going to the 'real' site.
We do the best we can and push our partners to do the same. Over the years it is getting better, but it is not close to what consumers want.
That said, speed is a much bigger issue in some markets (rentals in cities like Munich) and much less in others (buying a house out in a village).