What's a dead giveaway that someone is a bad person?

When they do not return the grocery cart to the cart corral.

Mean to animals

"You can easily judge a person's character by how they treats those who can do nothing for them."

... or something really close to that. I'm too lazy to look up the actual quote right now.

If they're mean to waiters, cashiers, janitors, etc.

Everyone can be a friend when it's easy and convenient. It's during the bad times, when they suffer and it's not so easy to keep cool, that their true values or lack of come to light.

Being unable to admit they are wrong or don't know something. I feel like it's one of those traits that snowballs into someone coming off as obnoxious and elitist

God, reading all these comments while baked in a hammock was a trip. I highly recommend the cart saga.

I'd say it's when they get angry when you tell them the impact their behavior is having on you, instead of actually trying to have a discussion and sort the problem out.

Or they get angry with you for enforcing your boundries.

Not to bring Trump into everything, but yeah... Trump supporters. Bonus level of shittiness if they have a maga hat.

They enjoy the suffering of others.

How often and long they twirl their mustache.

This is not a dead giveaway as it will take some time and observations but, how often they react to adversity by blaming other people.

Reminder, if everywhere you go smells like dog doo, maybe check under your shoe.

"I call them how I see them."

"I'm just brutally honest."

"I'm just telling it like it is."

These phrases are used exclusively by rude, obnoxious, condescending assholes trying to justify being shitty to other people for no reason.

"I like people/politicians who tell it is like it is!"

This always means expressing popular grievance with a particular style that scapegoats everyone else for a group's problems.

They don't like animals.

Extreme racism.

Folks who opt not to clean up after their dogs. Particularly in public areas.

When their opinions are... very extreme.

Earlier today, someone told me that they'd wish someone were no longer living if they mentioned liking a certain type of pizza. It definitely wasn't said in a joking tone either (not that I'd really want to be around someone who made that type of "joke" in the first place) - that was a pretty obvious indicator that they were a bad person in my book.

It was done under the guise of "I don't like to sugarcoat things" 🙄

An unwillingness to admit fault, and/or learn from one's mistakes. It's the biggest and reddest of red flags.

How they treat their waitress at a restaurant. Big red flag.