People who do necessary work but do not get paid very well for it: garbage collectors, hospital aides, housecleaners, retail cashiers, etc. Those who were raised in the comfort of middle-class suburbia are the biggest fans of pseudo-"street" hip-hop messages that confirm their already held feelings of superiority to those who are forced by social conditions to live the "authentic" "real" inner-city urban lifestyle, the real "street". Instead of focusing on economic and social conditions, this song allows the middle-class to feel morally and ultimately superior to the lower classes.
"I don't want no scrubs. A scrub is a guy who can't get no love from me." (Which is actually a double negative, which if correctly read, actually means "A scrub is a guy that can get love from me". But apparently the lyricists are too illiterate to notice their grammatical errors).