JKR's animal-like descriptions

[MinervaEvenstar]

Ever notice how many times JKR uses comparisons between animals to describe her characers?

Pansy - face like a pug
Umbriddge - face like a toad
Petunia - face like a horse
Peakes - (Dudley's friend) face like a weasel
Voldemort - face like a snake
Trelawney - insect due to her huge glasses
Marcus - troll
Pince - vulture
Sirius - bark-like laugh
Dudley - "pig in a wig," according to Harry in book 1
Snape - "overgrown bat" when his black robes billow around him

I've probably missed some, so feel free to add them! I was just wondering what everyone thought about it. I can understand either position:
Good - It's a good way of describing people because it gives a clear image of what they look like. Personally, I really like the Voldemort and Sirius ones because it gives an insight to something else about them. (Voldemort = Parselmouth, Sirius = dog animagus)
Bad - It becomes a bit redundant when so many characters have animalistic faces. Maybe it doesn't make a clear image. Personally, I can visualise all of them excep the Trelawney one. Big glasses or not, I just cannot see a person looking like a bug.  

[Drakie Cakie]

And Lupin!
Remus Lupin- Lupin is derived from Lupus, which means wolf in Latin. I realize he's not described like an animal, but his name is a give-away to his canine-ness.

 

[Nicky Cade]

You know, I noticed that as well! With characters like Sirius, I can see why she would use animal metaphors- Sirius spent a long time trying to be a dog, and then I believe spent most (if not all) of his time in Azkaban as one. I'd be a little surprised if he hadn't taken on some dog-like qualities. But, as for the other characters, I can't think of any direct reason why she would choose animals to describe them. Perhaps because there aren't that many people who don't know what those animals are, and would understand the imagery. Or many Miss Rowling is just an animal fan ^^.