If Bob had decided to honestly put down his thoughts on paper, what is the most interesting event that he could have discussed from To Kill a Mockingbird?
This is certainly an interesting question, since critics have always speculated whether Bob may have had some kind of sexual relationship with his eldest daughter. A single statement by Tom Robinson during his testimony presents this possibility: When Mayella reached up and kissed Tom inside her house,
"She says she never kissed a grown man before an' she might as well kiss a nigger. She says what her papa do to her don't count."
Although this could have simply referred to innocent kisses on the cheek, the tone seems to have a more sinister intent. It is apparent that Bob must have beaten Mayella after finding her kissing and hugging Tom, and it may well have not been the first time. During Atticus's cross-examination of Mayella, he asks her if Bob "is easy to get along with?" Mayella responds that her father is "tollable, 'cept when--"
"... Except when he's drinking?" asked Atticus so gently that Mayella nodded.
Mayella denies verbally that Bob had ever beaten her, but it is obvious that "someone who led almost exclusively with his left" did the damage to her face.
I believe an honest written explanation by Bob concerning his true relationship with Mayella would have cleared up many of the questions left unanswered, and it would probably have been the evidence that proved Tom's innocence.