I have figured out a very simple way to identify transparent logos much easier!

In all modern graphics software, transparency is visible because of the use of a checkerboard pattern.

I used this concept to create a Stylish style for the site, to mimic this behavior.

I am planning to make this a permanent change on the site soon, but i dont have access to the css files at the moment.

SCREENSHOTS: (BEFORE vs AFTER - click to enlarge)

Stylish Code:

.node .content .field-type-image img {
background: #eee url('http://i41.photobucket.com/albums/e257/MaFi0z/checkerboard.png') 0 0 repeat !important;
}

Enjoy!