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.