Villains: Part Four

Well, this will be the last post in my series on villains, so I have a couple of different topics I'll touch on. Both are basically questions on matters of opinion.
The first one is on villains' appearances. There are cases, such as in the Louis L'Amour books where the villain is usually ugly or 'greasy' in appearance, maybe has a disfiguring scar, or something of the sort.
Then there are cases such as in C.S. Lewis' The Lion, the Witch, and the Wardrobe, where the villainess (i.e., the White Witch) is deceptively beautiful.
Which do you prefer? Or, does it just depend on the villain and the circumstances?
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The second topic I'll mention (I thought it kind of fitting for the last post in my series on villains) is on the matter of the villain's demise. There are basically three main categories that said demises can fall into:
If I may use Louis L'Amour as an example again, the villains in his novels always, always get what they deserve in the end. Be it hanged in the town square, shot in the street, run out of the country, or trampled to death by a herd of cattle, rest assured: a L'Amour villain will, one way or another, get what's coming to him.
Occasionally I come across a book in which the villain converts, repents, or otherwise changes his ways at some point in the story. Nineteenth-century author E.D.E.N. Southworth is notorious for doing this in some form or other. It can be a very good plot twist if well-executed, but infuriating to the reader if done clumsily.
Finally, there are those rare and bizarre cases in which the reader follows the desperate plight of the hero through the entire book, loathing the villain more and more with every page turn... and the villain wins in the end. (Note: if you are an author who writes this sort of story, it may be in your best interest not to say anything to me about it. I have a very heavy volume of The Literature of England sitting next to me right now, and I may have to come and pound you with it.) Pray, tell me: what is the point of reading a book if the bad guy wins in the end?!?! I usually try to keep an open mind about different approaches to plot execution, but I cannot abide a story in which the villain ends up winning. This also applies to those even more bizarre 'trick ending' cases, in which the guy you thought was the bad guy all along is really the good guy, you just couldn't see it because you were in the guy-you-thought-was-the-good-guy's perspective the whole time. Technically, in such instances, the good guy wins--but the reader is still upset because he thought the guy who ends up the winner was the bad guy. The movie The Prestige is a good example of this kind of trick ending--and a good example of viewer reaction. My entire family was furious over the way it ended. If you as a writer want your readers to hate you and boycott your writing, then by all means use this plot ploy. Otherwise... hopefully you get the idea.
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Both the issues in this post are basically matters of personal preference, but that leaves plenty of room for discussion. What are your thoughts?