My favorite two are saying he can't help with class assignments because of a lack of time followed by it being unfair for a student's grade to be determined by the willingness or capacity of a stranger to help and he is ready to discuss this with the teacher, principal, or school board. It shows that he does care and wants to help, but lack of available time really is the issue.
My third favorite is ( ) Please do not write to me again.
He was pretty misogynistic and kind of nuts, but I do enjoy his books, especially The Moon is a Harsh Mistress, which is a great example of how to use a science fiction setting to retell a historical event.
I think that it is unfair to say that about Heinlen that he was misogynistic. The women in his books were strong and capable. He may have been sexiest, but he wasn't misogynistic.
Another thing to note is in many of the books, he changes the point he is trying to make. He is an interesting author as he covers a vast number of topics.
I don't know if I would agree with you. Maybe he wasn't misogynistic earlier in life, but by the end? Did you ever read Friday? It's kind of disturbing. Yes, the main character is a woman who is better than a normal human through genetic engineering. She also enjoys getting raped.
That idea is also a very common thing in Ayn Rand's writing too, which he's said he was quite influenced by her writing in an interview in the mid 70s.