Hmm I do wonder what the cyrodil clan was like before they got the ability to blend in.
Probably ugly as hell. Maybe they had a pureblood in their clan or two and they all decided to change their appearance.
Maybe the Volkihar should go the shrine of Clavicus Vile and get a face-change there for a thousand gold

Eh, it's kind of a double-edged sword for me, and I can't decide which I like better. One the one hand, I absolutely LOVE how incredibly monstrous the vampires in Dawnguard are, if only because I started getting tired of the more modern view of vampires, being more desirable supermodels than anything else (I hate to use Twilight as an example, because I know there are others doing really similar things, but that's the most obvious). Vampires, to me, were always supposed to be merciless creatures of the night, something you should very much fear.
But on the other hand, even the more traditional monstrous vampires were six and seduction personified. Stoker's Dracula had quite a bit of not-so-subtle sixual symbolism in it. That was always kind of the horror with that book, Dracula used his seductive prowess to spread his influence and turn people into vampires. It was sort of the dark side of six, just without the brutality that usually comes with [censored]. So having the Volkihar vampires have hideous bat faces kind of defeats that purpose.
I'll probably never end up making a decision on this, lol. I guess I mostly appreciate the hideousness of Dawnguard's vampires because I like that Bethesda, whether intentional or not, is reminding us that vampires are a dangerous, heartless evil to be reckoned with, and a subject of horror stories, not just a supernatural teenage hearthrob.
See, the thing is the Volkihar fit the bill with ugly merciless creatures of the night. They are terrible, they are predatory and they are monstrous. They are the type of beast that will lurk in caves and stalk you cities at night time. Then they enthrall you and then take you away to the castle so that you can be fed on in their table slowly while you are aware, but otherwise unable to do anything. They kidnap people, they eat people, they are the savage creatures born out of a nightmare. Volkihar were never meant to have the Dracula influence, yet they do have some. They are more "Nosferatu" and "Boogeyman" than "Dracula"
Now the Order? They are monsters in their own right, but to a much more insidious and subtle degree. They are the people you would invite over to have a chat with on a fancy dinner table, sipping wine and talking politics, day to day stuff and etc. You could be their best friend, and yet their favorite meal. You can end up shaking hands with them over a board game, then end up in a grave somewhere. They might pass on as nice influential counts and nobles, but the fact that they are told to "manipulate the hand of society to mete our agendas" simply tell us they hold a good measure of power, especially since they are in the province that is the seat of an Empire. Most likely whispering poison in the ears of mortal rulers, as Potema engaged with vampiric generals in the time of war.
They are literately lions in sheep's clothing. They may dress themselves as good people, but most of them are manipulative and deceitful, sneaking into town at night into a boudoir to nibble on the succulent neck of a young woman. Seridur used vampire's seduction to entrall Relfina, Roland's lover in the fourth game. He was said to have been coveting her for quite awhile and harbored some lust for her. Being children of Molag Bal, who created the first vampire by [censored] her to death, there are obviously some dark sixual influences in there.
Take Seridur trying to seduce another man's lover, Movarth seducing Alva, who in turn seduced a man that was willing to burn down his own home and move in with her. There is always that dark, manipulative sixual seduction in there when it comes to some vampires of the Cyrodiilic clan. They fit the bill with Dracula. Cultures, well-mannered, civilized, seductive.
I love that about the two clans.