Smelling bad, showing off bare feet and being too fat are among the reasons air travellers can be ejected from flights.
While appearing to be drunk may be expected to be a red flag to plane crews, the dozens of reasons are reportedly detailed in the airline's "contract of carriage" passengers sign up to upon ticket purchase.
See also: Police drag man from overbooked flight
See also: Girls,10, banned from wearing leggings on flight
You may not have noticed these conditions - the documents can be as long as 37,000 words long.
Americans are examining the conditions for passengers following the ongoing controversy over the United Airlines passenger dragged off a flight because the airline overbooked it.
United Airlines is facing calls for a boycott
The largest US airlines — American, Delta, Southwest and United — have similar conditions for denying passengers, USA Today reports.
They are said to include those who are barefoot or not properly clothed, who or cause a malodorous condition and who appear intoxicated or under the influence of drugs.
Those who are unable to sit in a single seat with the belt properly secured or put the armrests down can also be removed.
Anthony Sabino, a lawyer in Mineola, New York, told the newspaper: "There is no constitutional right to get on a plane.
United Airlines has been under fire over the controversy in Chicago involving a passenger on an overbooked flight
"If you don't want to be searched at the airport, take Amtrak, jump in your car."
Steptoe & Johnson partner and aviation law expert Roy Goldberg said: "Those contracts are well thought through.
"They are generally fair and balanced, and they reflect the market.
"As a general matter, passengers have rights, but airlines have rights, too."
Dr Dao being dragged off the plane
The boss of United Airlines has apologised for a third time after a passenger was violently dragged off an 'overbooked' flight.
Worldwide boycotts were called for after footage emerged of 69-year-old grandfather Dr David Dao being evicted from Sunday's flight to make way for staff.
He was seen being ripped from his seat after refusing United's of $1,000 in compensation as he said he had patients to see the following day.
As Dr Dao was forcibly removed his head was slammed into a nearby seat rendering him semi-conscious and blood streaming from his nose and mouth.
In an attempt to quell the backlash United CEO's Oscar Munoz said that employees "followed established procedures" but in an email to staff called the passenger "disruptive and belligerent".
Oscar Munoz said staff were left with 'no choice' but to get the passenger removed
Munoz wrote Dr Dao refused to voluntarily leave the plane, with staff "left with no choice but to call Chicago Aviation Security Officers to assist in removing the customer from the flight".
The man was "politely asked" to get off the plane several times, according to Munoz's letter, "and each time he refused and became more and more disruptive and belligerent."
His email, labelled "tone deaf" by many, sparked further fury with hundreds demanding he resign as more than four percent - $1.6 billion (£1.1 billion) - was wiped from company shares yesterday in response.
A beleaguered Mr Munoz issued a third statement he sent on Wednesday in which he said the company finally took "full responsibility" for the incident.
It read: "Dear team
"The truly horrific event that occurred on this flight has elicited many responses from all of us: outrage, anger, disappointment.
"I share all of those sentiments, and one above all: my deepest apologies for what happened."
Dr Dao is still recovering in hospital
"Like you, I continue to be disturbed by what happened on this flight and I deeply apologize to the customer forcibly removed and to all the customers aboard.
"No one should ever be mistreated this way.
"I want you to know that we take full responsibility and we will work to make it right.
"It's never too late to do the right thing. I have committed to our customers and our employees that we are going to fix what's broken so this never happens again.
"This will include a thorough review of crew movement, our policies incentivizing volunteers in these situations, how we handle oversold situations and an examination of how we partner with airport authorities and local law enforcement.
"We'll communicate the results of our review by April 30th.
"I promise you we will do better."
The flight from Chicago O'Hare International Airport to Louisville would have taken five hours to drive.
More than 80,000 people so far have signed a petition to the White House asking for an investigation into the incident.
Passengers said they had already taken their seats when they were told the plane was overbooked and some people would have to "volunteer" to make way for four extra airline staff members.
Other passengers filmed the tussle
When no-one put themselves forward, they randomly selected Vietnamese-American Dr Dao and his wife to get off.
Passenger Jayse Ansprach, wrote on Twitter the passenger had explained he was a doctor needed in hospital the next day - at which point staff "decided to use force" with the help of Aviation Security Officers.
One woman can be heard on the 31-second clip shouting "What are you doing? No, this is wrong. Look at what you did to him."
Hundreds of people have people have taken to social media to say they will never fly with the airline again.
The Department of Transportation whose staff removed the man said it would review the incident and one employee has been suspended pending an investigation.