I can see it swinging a couple of ways. But it also depends on how naturally .... "Different" (Fugly) Your orcs and trolls are.
Depending on the art in the books, your trolls can be very very a-symmetrical fugly with half tusks on one side, spiraling horns on only one side of their head, fugly blobs of melted butter in clothes... OR.... large body types with muscles longer than normal arms, and some symmetry.
Now... in my games.. it runs the gambit. Just like someone else above stated. You have some UUUUUUUUGly trolls (( like the ones on the front of the Tir book. That spiral horn off one side of the head still makes me go ugg)) and some more attractive trolls. Now.. even more attractive trolls, are going to be trolly.
I play trolls. (( orcs, ect. I don't think I've ever made a 'human' Shadowrunner.... )) But my trolls are not the very very fugly a- symmetrical types. They tend to have the symmetry that I prefer. If they have one horn they have another that matches it. Same with tusks. Also, the dermal deposits that they have are seldom the huge nobby grossly lump of wax kind you find in some of the more fugly pictures/drawings. That doesn't mean they don't have them, but again, symmetry (more or less).
If a troll was born with very a-symmetrical features.. (( say one curly fugly horn on one side of his head but not the other)) I can --totally-- see him having it removed and a more attractive pair of horns put on. Or.. if he has tusks on the left side of his mouth, I can see him getting ones put on the right. Make it look nice. (( well nicer)). If he's got giant globby gnarly dermal deposits, I can see him getting them shaped and made to look better.
Note none of these would make the troll look "human" It just makes them look less fugly. It'd be the same thing like a normal pretty girl with a huge nose, getting a nose job. If she doesn't tell anyone, chances are noone would know. They'd just think she was pretty. Or if a normal human had alot of warts on their head, and got them removed. Noone would say "That guy doesn't look human" they'd just think he looked normal. If the troll does this. (( gets more attractive horns, or tusks or something)) I see no problem with it what so ever. Because... .really. Who'd know? You're not 'hiding' your trollishness.
I can even see some people getting stylized ones. Say you had normal troll horns but wanted bull like horns. Or you had bull horns and wanted normal ones... Say you had thick tusks but wanted two pair of smaller ones... or you had two smaller ones and wanted one thick set.. ect.. again... Cosmetic that changes but doesn't "hide" your trollishness (( or orcness))
I think where you start getting problems isn't when you're trying to be a more attractive troll, but indeed when you try and be something you're not.
There's a difference between "I have horns that match, tusks that match, my skin doesn't look like a lunar landscape of globs" and "I wanna look HUMAN"
It'd be then, that you're getting into social penalties.
A girl gets a nose job. Noone blinks. (( unless it's botched))
That same girl splits her tongue down the middle and gets implants under the skin of her forhead to give her horns and... it's a freaky thing. The pic I use for my avatar here is one of my more favorite images of a troll in Shadowrun. And I think the main reason is that he does have that Symmetry, while CLEARLY retaining his Trollishness.
(( This guy))
http://dc244.4shared.com/doc/voNzakex/preview001.png