Flight attendants scrutinize the passengers on their flights more than they let on, and even though most people think of them as little more than servers in the sky they're trained to spot problems before the passengers are finished boarding.
In fact, most flight attendants start to check out the passengers on their flight while they're waiting, so what do flight attendants look for as they size up the folks on their flight?
For a start they check to see if you're inebriated:
According to Sjaak Schulteis, who was a cabin attendant for Lufthansa for 30 years, drunk passengers can be refused entry aboard the aircraft.
"If a guest coming aboard is drunk or intoxicated by any drug, it can happen that he or she is not allowed to enter the plane. [...] The first impression is often the right one, and we do refuse passengers who might be a danger for the safety of that flight. So far I have refused four passengers and was luckily backed up by the purser and captain. All of these were drunken passengers."
They also check to see if you're muscular, so they can go to you if they need backup:
"I consider this person a resource for me. In the event of an attack on the flight or on me, these are my 'go-to' people. If a situation looks like it could develop, I'll privately and discreetly ask one of these people if they would be willing to help us if necessary. Help might involve subduing or restraining an unruly passenger. We hope it never happens, but we will prepare just in case it does."
And they always keep their eyes peeled for other airline employees, because they can be really helpful in a pinch too:
Bridger says that she tries to " learn if we have any passengers who are airline employees, particularly crew members who have been trained in the in-flight procedures."
She says "They've been trained in what to do in an emergency, whether medical, mechanical, etc. They know how to handle the situations as well as I, and are trained to become an instant 'team member,' fitting right in immediately if needed. They are an invaluable resource for me, and I like to know who they are and where they're sitting."