I think a lot of that has to do with it looking... disportionate. His arms are huge, while torso is more compact... and his head is too. Compared to the 300 training (
http://z.about.com/d/comicbooks/1/0/8/D/FCJG300-0088.jpg ), it looks rather freakish. The other picture has the same compact torso, but a better sense of proportion.
The conventional wisdom is that men think women prefer more muscle than women actually do...and women think men want them to be skinnier than men actually do. And I mention that because I think your preference is relatively normal
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I'd actually be interesting in hearing a good exercise regiment for toning only - slight building, and not with the real intent to increase muscle mass. I've found that information to be remarkably hard to put into a coherent routine. It's easy to get general fitness information/toning and more hardcore muscle building... but none of it seems comprehensive in the middle.
If anyone is in the know-how, what I'd be curious about is about tapering the torso - to get the V shape. I know most of it will be about aerobic, but some muscle definition is required to emphasize it. I'd also be interesting in deltoid work that would be more bulk-orientated - from what I understand, that's the only way to give the appearance of broader shoulders. I think most males would gain the most from these two, from what I know of physical attractiveness.
And it's not even academic - there is reasonable return on investing time into making one more attractive!