In the world of casting people are divided into categories.
When a casting goes out to the talent agents, they usually specify a certain look or attitude for the people they wish to see. This is what the clients (advertising agency, creative team, director/producer etc.) wish to see representing their products or playing their characters. Some of these may seem stereotypical - but remember that it is the perception of the public (consumers) which sets these standards not the casting directors or even clients.
What we ask for and what we want:
Models (also referred to as "Beautiful People") - Many of you reading this may have been told for years how beautiful you are. This unfortunately does not mean you would meet the industry criteria: at least 5′9″ for women and 6′ for men, gorgeous enough to be on a magazine cover or cosmetic ad, have perfect proportions and body type (no cellulite) and (usually) be 16 to 25 years of age. They are often cast as "Bikini types" or "sexy types" for cosmetics, perfume, lingerie, automobiles etc. Occasionally we will be asked for model-types in older age categories but they are generally considered lifestyle.
Lifestyle models (also known as "Commercial Type") This category usually encompasses the 25 and up age group who are more "real looking models". This does not mean they look like the people you see in the grocery store, this means they look like the people you see in commercials for condo's, country clubs, banking, cruises, department stores etc. They are considered less threatening to the average person than the "Beautiful People" yet they are hardly what you see in everyday life. They are thin, usually over 5′6 for women and 5′10 for men, very attractive and well-dressed in a "crisp and neat" sort of way.
They usually look very "Proctor and Gamble", which is another name used for this category. The name comes from the years of advertising done by this company using very attractive, healthy-looking, yet thin and trim, "All-American types". This means blonde, light brown hair or auburn and light eyed for Caucasians and light-skinned, often straightened hair "Cosby show types" for African-Americans. No one wears glasses, has crooked teeth, big hips or large noses. They are the "pretty people".
Most of your young to middle-aged moms and dads types, grandmothers/fathers (unless character) business men/women (although they are permitted fashionable glasses), housewives (unless character-y) athletes and yuppies/preppies used in commercials are found in this category. They are athletic, though never sweat, active but never tired, and if they do get a headache, cold or bad night's sleep they still look good.
"Upscale" types are usually found in this category . They can be 20's to 70's. They symbolize wealth, success and a happy, expensive lifestyle – in both their wardrobe and demeanor.
Real People. Luckily, over the years advertisers have added this category. These people are still not too far from pretty but may have a small flaw or two. Again, they do not look like most the real people I know, but have a "character-y look" (not to be confused with true character types) This means that they are still attractive to most people but not quite pretty or handsome by industry standards. They are neat and clean looking. Men might be balding or have a few wrinkles. Women might be a little plump or have less than perfect hair. They are what advertisers see as the average person.
Many times they are booked as the friend, neighbor, bookkeeper, secretary, cashier, teller, nurse, factory worker, cowboy, officer, paramedic etc. Housewives are also sometimes found in this group, especially if the spots have humor in them.
Character - these are the rest of us. Fat, very thin, big noses, funny hair, bald heads, crooked teeth quirky expressions and (usually) a sense of humor are all a big plus. I personally love these castings the best for two reasons. First of all the people are usually well-trained as they have never been able to skate by on their looks and the roles are usually funny or very challenging (versus the "wear a swimsuit, smile, turn around and tell us you name" jobs, we cast all the time).
The roles can include sports fan, detective, trailer-park inhabitant, biker, salty-dog (must be over 60) funny grandma/grandpas, Gen-Xers (piercings, tatoo's and all) artsy types, eccentrics, intimidating bad guys, funny athletes, crazy neighbors and anything else you can think of that doesn't fit the other categories.
Find your niche and enjoy it. Don't try to be something you're not. There is work out there for everyone!