I think the line about "The only blood that's any cleaner is the blood that's blue or greener//Without either you just get meaner and the blood you gave gives you away" is referring to the fact that only way someone betters themselves is by being born to a higher social class ("blue blood") or by getting money ("green blood"). The "meaner" part has a double meaning in that it's meaner as being mean and meaner as is being "common" (as in "regression to the mean"). Blood always give you away, it proves who you are in several ways: how you act (in the social meaning), who you are (both social and physically (DNA or blood type)), and just how much blood (and sweat) you're willing to put into something (which may be making that "green" by criminal enterprises).
I think the line about "The only blood that's any cleaner is the blood that's blue or greener//Without either you just get meaner and the blood you gave gives you away" is referring to the fact that only way someone betters themselves is by being born to a higher social class ("blue blood") or by getting money ("green blood"). The "meaner" part has a double meaning in that it's meaner as being mean and meaner as is being "common" (as in "regression to the mean"). Blood always give you away, it proves who you are in several ways: how you act (in the social meaning), who you are (both social and physically (DNA or blood type)), and just how much blood (and sweat) you're willing to put into something (which may be making that "green" by criminal enterprises).
Just my two cents on a song I love.