If you are going to Dessau expressly to see the Bauhaus, then you must stay at the B&B at Kleinring 5 in the Torten housing estate. I will admit that Kleinring 5 is not very conveniently located. The Torten neighborhood is pretty far from the center of town, and the nearest restaurant is a bit of walk. However, Kleinring 5 is a genuine Bauhaus house in a Bauhaus neighborhood. There is another B&B right across the street from the Meisterhauser, but staying at Kleinring 5, you trade location for experience. When else are you going to sleep in a house designed by Gropius? Moreover, Kleinring 5 is close to the Steel House, the Mendelssohn Center, and other peripheral Bauhaus sites.
The owner is extremely nice and accommodating. The breakfast was very generous.
I definitely recommend this inn.