In The Glass Menagerie, alcoholism is not major or explicit, yet becomes a symbol for all undesirable activities. Amanda uses alcohol as an umbrella to cover any un-ambitious activities that her son takes part in, including writing, reading, and going to the movies. When she asks if Laura’s gentleman caller is a "boy who drinks," what she really wants to know is whether he is the kind of boy who drinks, is rowdy, goes out at night, and doesn’t care too much about his future. Because her husband drank, Amanda associates alcoholism with him, and therefore with irresponsibility and abandonment.
Because it is the one fault she claims of her missing husband, Amanda sees alcoholism as the root of all evil, using it as an overarching umbrella to characterize everything that she believes is wrong about Tom's way of living.