Another way that smart people can come to not-so-smart conclusions about others is if they fail to establish a baseline. The guy in front of you may be making lots of eye contact, smiling often, complimenting you, nodding, even touching your arm occasionally. You could conclude that this guy must really like you, until you realize that this is how he is with every person he meets. He in fact is showing you no interest above his normal baseline, so all your observations don’t quite lead where they ordinarily would.