After you have known people for a while, you realize they are defective. They’re cheap, crude, pushy, ignorant, loud, and unattractive. How did this happen? How did people who seemed so elegant and gregarious become the varmint-like creatures you want to avoid? What made them change into the dirty froth of humanity right before your eyes? Believe it or not, science has done some research on this phenomenon.

Highly defective people (HDP) have several common characteristics that reveal themselves over time. Their habits astound and mystify us. They might look different on the outside, but on the inside they are very much alike. They share common attributes that make them a kindred clan. One or two of these traits alone wouldn’t qualify them, but with a cluster of seven, you are in the presence of a HDP. In no particular order, here’s what to look for:

1. Me, me, me.

This is the one person defective people love to talk about. In the June 2013 issue of the Journal of Research in Personality, German researchers discovered that people who refer to themselves more often by using first-person singular pronouns like “I,” “me,” and “myself” are more likely to be depressed than participants who used more pronouns like “we” and “us.” The researchers studied 103 women and 15 men using psychotherapeutic interviews followed by questionnaires about depression. They found that participants who said more first-personal singular words were more depressed.

But wait — there’s more. They were also more likely to be difficult in other ways. They inappropriately self-disclose, constantly seek attention, and have difficulty being alone. (Maybe they don’t like the company.)

2. Bubble-busting. Shelly Gable and her colleagues are relationship scientists who study the patterns of communication between people. They’ve found that only supportive, encouraging comments celebrating the good news of others is what makes for a solid relationship. They call this active-constructive responding (ACR).

However, one of the communication patterns they looked at is particularly nasty. Active-destructive responders quash any good news they hear from you. Got a raise? “Most of it will be taken out in taxes.” Got a new love? “It’ll never last.” The researchers should have called these folks the Buzz Killers.

3. Materialism.

“Money can’t buy you love, but it can buy almost everything else.” This is the mantra of the materialists. But why are they so unhappy? In the July 2014 issue of Personality and Individual Differences, researcher Jo-Ann Tsang, from Baylor University, and her colleagues asked this question. What they found is interesting: Materialists lack gratitude. They are less satisfied with their lives because they are not focused on what is positive in them. As a result, they can’t get their psychological needs met, and set an unrealistically high expectation of what a new possession will bring. When the expectation isn’t met and the hope for it dashed, the positive feelings drop. Bummer, let’s go buy a Hummer.

4. Pessimism.

The pessimists among us see negative events as permanent, uncontrollable, and pervasive, whereas optimists see negative events as temporary, changeable, and specific to the occasion. Martin Seligman, in his 1990 book, Learned Optimism, explained that pessimistic thinkers generally take negative things to heart.

Since then, there has been much research to back this up. Pessimists explain negative events happening to them as stable, global, and internal: stable meaning they won’t change over time; global in that it reflects their whole life; and internal in that the cause of the event happened because of them. But when good things happen for a pessimist, it is the other way around. It is unstable and will change, it was only in this specific case that the good event could happen, and they don’t believe they had any role in making it come about.

Optimists are exactly the opposite on all three dimensions. For them the glass is always half full. For the pessimist it isn’t just half empty, it’s their fault.

5. They count (and recount) their less-ings.

The focus is on what’s wrong, not on what’s strong. Instead of counting their blessings, highly defective people dwell on the opposite. They ruminate over the negative things in their lives and, as a result, their sense of well-being and physical health suffer.

In 2004 Robert Emmons and M. E. McCullough edited an impressive volume: The Psychology Of Gratitude. Time and time again, the research showed that focusing on what you are grateful for improves your well-being.

The November 2014 issue of O: The Oprah Magazine sings the praises of gratitude in its cover story. The problem, of course, is that HDP never read stuff like this.

6. A fixed mindset.

People with a fixed mindset don’t believe they can change. They see themselves as unable to make significant changes in their abilities. Carol Dweck of Stanford University proposed in her 2006 book, Mindset: The New Psychology of Success, that some people see their innate ability to succeed as fixed, while others believe that hard work, grit, training, and learning can help them achieve success.

Guess who’s right? They both are. As Henry Ford once said, “Whether you think you can, or you think you can’t, you’re right.”

7. Procrastination.

“Why do today what you can put off until tomorrow?” might be the mantra of HDP. Since 1997, research on procrastination has demonstrated that while procrastinators might get a short-term benefit from putting things off, the long-term benefit is that they end up feeling worse than those who get on with it. In his 2010 book, Still Procrastinating? The No Regrets Guide to Getting It Done, researcher Joseph Ferrari thinks we should reward people who get things done ahead of time.

In a 2011 paper in Psychological Science, Gráinne Fitzsimons and Eli Finkel report that procrastinators who think their partners will help them with a task are more likely to procrastinate. If you live with a HDP, let the dishes pile up and the garbage overflow. It’s the least you can do to help.