Yeah. I think that there should be definitely be a minimum wage, which is pegged to some sort of measure of cost of living. Trade unions can negotiate anything on top of that for their respective professions, but if you're not represented by a powerful union that shouldn't consign you to poverty.
This article http://www.thelocal.de/20131121/germany-to-introduce-minimum-wage has some examples of the really low wages that German workers have had to deal with - office workers receiving €1.37 an hour, delivery drivers receiving €1.55 an hour in Mecklenburg-Vorpommern. This is pretty dreadful. The SPD wants to make the minimum wage €8.50 an hour.