Male or female?

Taking no time to think carefully, only seeing one side of things, only thinking about what they can see now and forgetting about the consequences.

When they always have something bad to say about someone.

These types are insecure because they know they’re not a nice person.

You had me until you demanded that some people need to change.
Why should they?
In order to please you?
What if they are happy?
Why should they change in order to gain your approval?
Couldn’t they also make the argument that you should be like them?
Why don’t you change?

Poor listening skills, not responding or acknowledging to what you say and turning the conversation back on themselves.

Obsessive about looks, body weight, personal appearance and puts down others for not measuring up.

Self absorbed and think their stuff is more important than anyone elses, their pain, upset, dramas are just fucking earth shattering and NOBODY else could ever understand how they feel.

Lose interest easily in relationships, all about the chase and initial romance but no staying power once the fireworks simmer down, change relationships frequently.

Gossips.
Always chomping at the bit to share the latest dirt on somebody else.
Not trustworthy, will share your confidences in a heartbeat because they just LOVE having a new gossipy story to tell.

Jealous and envious of others and never miss an opportunity to diss someone else for their accomplishments or looks or whatever. Never truly happy for others good fortune or achievements, see them as a threat.

Has 1,500 friends on Facebook. Really, you accept anything.

Speaking in cliches, getting hung up on superficialities, not being able to see the forest for the trees, discomfort with abstract thinking.

That they are obsessed with themselves and their activities to the exclusion of interest in others.

That they are obsessed with their and others’ appearance.

They they don’t have interesting things to say about issues of the day or books or anything very deep.

When they act like they have nothing else to learn.

What criterion for “shallow” are we to use?

Superficial people are like a houses on TV. They look good, but when you go behind the scenes, you realize there is no roof, walls are missing and the stairs don’t go anywhere. They are good looking shells.

Lots of mirrors

To judge another human being “shallow” is, in my opinion, both unkind and unfair, and may say more about the judger than the judgee. How can anyone possibly know another person fully enough to make such an uninformed judgement? After all, to a blood relative, spouse, close friend, co-worker or even casual acquaintence, that so-called “shallow” person may be the kindest, sweetest, most generous, supportive and important person they ever met.

When you talk to these people, they don’t hear a word you say, but are thinking about what they’ll say next. Don’t waste another nanosecond of your precious time with these self-absorbed nonentities. Be a good listener yourself: Listen for wind whistling through an empty brain pan, and, if you hear that sound, run, don’t walk, the other way.

Another good indicator is that the person is emulating the latest trendoid seen on media. Same hair, same makeup, same mannerisms, same enunciation, same nose, same ass. This is particularly unattractive if the person—male or female—is west of 50.

When a person’s immediate response to practically everything is an excited “OMG!!!”, that person is advertising to everybody in earshot just how shallow they are. Also, the more a person can’t wait to share the latest rumors & dirt about some entertainment figure, the shallower that person is.

Also, the spot on observations shared by @Hipster.

Someone who is friend with you so they could look better. I have friends that are like that when I was younger. Since I was plain Jane, if they were to stand next to me it automatically increase their attractiveness.