You realize that this was not a one-off event, right? Do I really need to find the youtube compendiums of Biden creepy behaviors?
The "any man" comment is a nonresponsive copout IMO.
As for knowing, that is your word not mine. But in the interest of discussion, a few things. One, I've had a long career in enterprise sales and a lot of my success has been due to my ability to read people (relatedly I test quite high for this in the Predictive Index assessment, if you are familiar with it). Two, I grew up Catholic 15 minutes from Scranton, and while my family to my knowledge did not have a sexual abuse problem, it did have the unfortunate dynamic common to many such families in the region in which tough problems were not discussed, instead they were buried, I believe in hopes that they would just go away. The Penn State / Sandusky / Paterno example down the road is one of the most horrifying examples of this. Personally though, I know several people who were abused by family members. One woman (still a good friend), when it finally came out that she had been abused, her family's reaction was "oh, we thought he only liked boys." Third, I have two daughters, the older of which had no safety filter as a young child -- at a park once I turned my head for a minute and when I turned back a random guy was pushing her on a swing.
All of these life experiences led me to develop a finely-honed radar for behaviors such as Biden's. You may argue that this does not amount to "knowing," and grammatically you would be correct. And it occurs to me as I type this that I was unfair in my options of "delusional or lying" and will add "unaware" to the list. So
@timschochet, I apologize for the delusional comment.