Someone with nothing to sell but talk. Someone who literally tries to sell the air that he is breathing. A bum who tries to get money by talking passers by into his story. A bum who tries to use forceful words to get money.
"Look at that guy over there air hustling everybody that walks by" "Stop air hustling me man, I'm not giving you shit!" "I hate this corner that stupid air hustler is always pressing me for change" "Damn right I'm an air hustler I got everybodies money"