The ancient Persians debated all matters twice: once drunk, once sober. This seems wise to me. My first thought was that Congress should make this a new rule, because it would at least guarantee they were sober once.
But in our fishbowl world, the thing is impossible, of course. Incautious statements, prejudices, wild flights of bluster, would all be recorded for uh, posterity now, to the detriment of electability. Perhaps they could make a no cameras/reporters/recordings rule for half the debate, but I doubt the sense of honor necessary for such a practice prevails in all circles now. A pity.
We rely instead on emotional leakage, trying to sense from words used and words avoided what the reality must be underneath. This is notoriously inaccurate, and the guesses made as to Real Motive usually reveal more about the person making the guess than the group guessed about. I knew a brilliant psychiatrist years ago, a great influence on me both by his shrewd guesses and his wildly inaccurate ones. In discussing abortion, he once mentioned "those anti-choice people, if you get a few drinks in them, show that they pretty much just hate women." It was a chink in my liberal armor to hear this, because I knew some strongly pro-life people who didn't fit this at all. Eventually, I decided that while there might be several unattractive things about them that the doctor would observe if he got a few drinks in them, hatred of women wasn't one of them.
It is rather like getting a report from school about your child's misbehavior. There are accusations that you believe almost immediately about your child, knowing him well enough that you will be able to question him with some precision about the incident, and how far down this familiar road he went this time. Yet there are other accusations that immediately suggest that the school has not seen the problem clearly, and there is some other explanation. It is a misbehavior that is simply so out of character for your child that your suspicions are aroused. "Jack might do any number of things wrong which I would believe - but not that."