I always thought lumpenproletariat included the unemployed and criminal classes, typically the kind of low-lifes portrayed in Brecht's Threepenny Opera and one of its better-known songs, Mack the Knife or Mackie Messer.
Here's what Wikipedia says about 'em:
<<Lumpenproletariat (a German word literally meaning "rag proletariat") is a term first defined by Karl Marx and Friedrich Engels in The German Ideology (1845) and later elaborated on in other works by Marx. The term was originally coined by Marx to describe that segment of the working class that would never achieve class consciousness, and was therefore worthless in the context of revolutionary struggle.
<<In The Eighteenth Brumaire of Louis Napoleon (1852), Marx refers to the lumpenproletariat as the 'refuse of all classes,' including 'swindlers, confidence tricksters, brothel-keepers, rag-and-bone merchants, beggars, and other flotsam of society.' In the Eighteenth Brumaire, Marx describes the lumpenproletariat as a 'class fraction' that constituted the political power base for Louis Bonaparte of France in 1848. In this sense, Marx argued that Bonaparte was able to place himself above the two main classes, the proletariat and bourgeoisie, by resorting to the 'lumpenproletariat' as an apparently independent base of power, while in fact advancing the material interests of the bourgeoisie.>>