He's also exhibiting the effects of confirmation bias. A black family comes through and they're great tenants his brain is going to find a way to mold that into his pre-configured world view. "Wow, that was great. What a great family. An exception to the rule. There's one fella who's not making excuses for himself!" A black family comes through and they're terrible. "Typical black folks." A white family comes through and they're great tenants, "Par for the course." A white family comes through and they're assholes, "That guy (that individual guy) was a jerk!"Louis is confusing his experiences in dealing with the impoverished to that of racial identity. Were he over in some rural areas where white people had nothing then he would have a clearer idea of things. He would see poor people struggling to to keep a roof over their head by whatever means necessary when it is that or the street.
This isn't something he's doing consciously, it's something that's going on behind the scenes in his brain. Sometimes before the thoughts are even fully formed. And of course it's not just him. We all do it. Some are just better at recognizing and correcting for it than others.