Lyin' Ted and Crooked Hillary worked because dishonesty is one of the most politically-damaging characteristics a politician could have.
Being a little boring isn't the same.
Exactly
1. I would also add that once you are labled as dishonest, there is nothing you can do. You are considered dishonest for life. Being "sleepy" or "tired" or "weak" can be changed if you have a lively debate performance. Which Biden did.
2. Also, most voters like to see themeselves and their families as honest. Hence the dishonesty insult being so damaging. But almost everyone has a grandparent who is weaker and more tired than their younger days. It'll happen to everyone, its hard to hold that against Biden.