In what ways do we already know that the Ewells are "poor white trash"?

Burris Ewell only comes to the first day of school to escape the state forcing him to go. Bob Ewell is drunk most of the time. He lives with his daughter Mayella. There are many little kids even though his wife died a long time go. Mayella is clearly being abused by her father in the worst way. Bob Ewell prefers charity to working.