Here we see the entire gamut of what the web has to offer on this topic, from ugly to just plain horrible.

Parental Advisory Warning: in some cases it may not be clear which end of the dog is pressed against the glass. Rest assured that in every case it is, in fact, a face.

Zombie Husky

Creepy Basset

Evil Laborador

Nightmare Pug

Another Evil Laborador

What the hell is this?

And what's the deal with these butt ugly Labs?

There are some homo sapiens who deserve a shout-out as well:

Oh God, it's horrible!

I actually think this one is kind of nice:

Just when you thought children were safe:

Exorcist child:

Gold mine! 50 Animals Squashed Against Glass.

I think my favorite is The Barghest

But there are some other good ones on that page, such as:

and

and (possibly photoshopped)