We have a few times edited and reworked images created by others, [@Orpheus]/[@BrokenPromise], as the appearance fit for the character, but not the colors... Naturally, if we wish to post up online, we always ask the original artist's permission first. We also make sure to heavily modify the image so it is not merely a quick change to the original artist's work.
[hider=example]
Original:
[img]http://pre00.deviantart.net/eab7/th/pre/i/2015/002/f/6/mari_nguyen_kaydana_by_master_dust-d8cdish.jpg[/img]
Reworked version:
[img]http://pre02.deviantart.net/cda4/th/pre/f/2015/029/c/7/uniformed_sith_by_katherion-d8fy1hz.png[/img]
[/hider]

And naturally whenever one does something like that, in addition to asking permission prior to uploading to any public place, credit should be given as is due. Some artists excel at creating new pieces of art from scratch, others are good at making existing pieces into new pieces. Neither is better or worse than the other in our opinion.

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anyways... Let's get back to the discussion on hand...

Attractiveness of any character is largely in the eye of the beholder. (center eye, not one of the eyestalks). As such, it will never be attractive to all. Each character should have its own ideal appearance. For some, that ideal might not at all fit with the common definitions of attractive.

If your goal is "crotchety old man" you probably won't use a picture that most younger audiences would consider "attractive".