Isn't it annoying that in almost every tv show/movie the "Blonde" is the dumb one?

Agreed, unfortunately, a majority of blonds tend to lack intelligence. There's this annoying fatass blond girl in my class named Siena and she's got these huge, gargantuan boobs, in fact, I think the reason she's so stupid and senseless is because all her intelligence when to her chest. OKAY, THAT WAS RANDOM.

Naw its not annoying.

Do あなた watch Victorious? The dumb ditz in that one was a redhead named Kat. Just thought I'd give one example when it isn't true.

It does annoy me, my first crush was a blond, and trust me, she was no where near dumb.

Blondes are not dumb, people just think there all that and smarter because others wish they'd be better at things like most sporty girls.
Yes it is true that blonde girls are smart but that doesn't mean someone has to go out and say bad things または lies about that one girl, she may easily get offended によって her accomplishments she has done in life.
But the point is blondes are no different than other girls like brunettes または red-heads even if they have different talents または skills for sports または something.

I actually know of a few fictional blondes of both genders who are quite intelligent.

They're actually not, I mean in glee/グリー everybody is a stereotype, Quinn and Brittney are stupid and blonde. I can think of many other blond characters that ARE smart though, for instance the in 表示する True Blood, Sookie, the main character is smart, and Eric Northman is a manipulative genius.