If you look at adverts for 'front of house' type jobs, they almost always emphasise 'good presentation and grooming'.
First impressions are very important in business, and people want to know their valued customers are being received by someone with high standards of personal grooming.
As for 'good' looks, that's a little tougher ~ for one thing, there just aren't that many outstandingly good looking people around.
I mean, most people are nice enough looking, but movie-star type beauty is rare and those folks can usually get a better job than receptionist.
Mostly you'll find the public presentation type jobs are done by people who are OK looking, young-ish and very good with their grooming and personal presentation skills, rather than just good looking.
The dumb receptionist is a bit of a furphy, imo ~ you wouldn't last long as a receptionist in *most* places if you are an idiot, it can be fairly stressful and demanding.
And air hostess is a tough job ~ on your feet for up to eight hours at a time, dealing with cranky people who may also be scared, bored and demanding ... and it's not exactly 'glamorous' cleaning the toilets and splitting beers for rugby teams. You have to be fairly tough, AND well groomed.
Cheers! :-)