I believe Sr. Bush's comment that "I like him" is similar to saying, "I know it is wierd, but I like him. It is amazing, that I could like this person who is so beneath me." Sr. Bush knows it is uncharacteristic that he could like Clinton, yet he can't explain it.
Notice that Sr. Bush didn't say, "he is my friend," or "we are friends."
I think it is close to liking a bad habit or your inability to keep from looking at a train wreck.
Good point. I like smoking although I know it is toxic.