The use became more general, and the stereotype can be found all over the United States, and also in other countries in different forms. Australia has its own variation of the Valley Girl accent, as lampooned by Ja'mie King.

A Valley Girl can be described as materialistic, self-conscious, self-centered, hedonistic, physically attractive and sometimes sexually promiscuous. Valspeak is also a form of this trait, based on an exaggerated version of California English.

During the 1980s and the 1990s, the term metamorphosed into a caricature and stereotype of such women: a "ditzy" or "airhead" personality, and unapologetically "spoiled" behavior that showed more interest in shopping, personal appearance and social status than in intellectual development or personal accomplishment.

After the release of the Frank Zappa song "Valley Girl" in 1982 and the movie based on it in 1983, girls from all over the English-speaking world imitated the style.

The Valley Girl stereotype has declined in the 2000s for various reasons, one being an evolution into other stereotypes.

A certain sociolect associated with Valley Girls, referred to as “Valspeak,” became common across the United States during the 1980s and 1990s, and much entered teenage slang throughout the country.

Qualifiers such as “like”, “way”, "as if!", “totally” and “duh” were interjected in the middle of phrases and sentences as emphasizers. Narrative sentences were often spoken as though they were questions using a high rising terminal.

Valspeak is often spoken with a heavy accent sometimes associated with Californians. Words are spoken with high variation in pitch combined with very open or nasal vowel sounds.

Similar phenomena were registered around the globe in books, movies and on television. In diverse places such as Russia, Japan, Ethiopia, and Pakistan, parent movements and religious organizations were formed against this culture. Specifically, the upward inflection sentence was the most marked symptom of the global Valley Girl, marking these girls as part of the new global culture, saved mostly for the privileged.

Valley Girls, as is noticed above, spend most of their time shooping, esspecially at places like abercrombie and fitch, hollister, and other steretypically popular shops.

Other than this shopping fixation, valley girl fashion generally resembles a cross between prep and kogal, with emphasis on the color pink, boots, leg warmers, and being in style. They listen to mostly pop, techno, or 80s music, but aren't particularly interested in music, it's just what they know of.

Image from deviantart, info -save for the last paragraph, which is mine- from wikipedia.