Well, Trolls are the rarest meta-type before you add in the Fomori variant (which are native only to the British isles)....
On the good side, they basically look like smaller, cuter regular trolls... so they have that going for them... (the lack the dermal deposits, and are smaller in size).....
I would guess in this case, people would probably think he/she is a small troll that had some cosmetic surgery done (the dermal deposits removed).
But you start getting into the really "weird" and exotic variants and take them out of there native area and you are asking for problems IMO.
Nartaki
<SNIP>...a pair of additional arms and unusual skin hues. <SNIP>...
In fact, their only
non-human traits are the obvious ones: they possess blue, red, or
golden skins tones and two pairs of upper limbs (arms) which
originate from unique, flexible joints at each shoulder (making
them one of the rare 6-limbed mammals).
<SNIP>... The total population is believed to number less than five thousand.
Here, we have a good example. in Theory, if a PC makes a Nartaki, he is one out of 5000... out of a world population of 6 BILLION!
It's pretty safe to say no one has seen of them

So now you have a 6 limbed human with odd colored skin... At the very least, people are going to remember just where and when they saw him, even if it was just buying a soykaf....
Or, the more, um, traumatized(?) individuals in society might make a counting error and put lead into them. ("Blue skin?!?!? one, two, three, four arms?!?! BUG!!!!!" <BLAMBLAMBLAM>)