how come rumple's skin didnt turn all scaley atau whatever the right word is again after he brought magic back?

I think that correlates with how "evil/bad" he is. The lebih he is drawn away from his human self the lebih scaley atau inhuman he becomes. There is a big difference in the rumple who had just obtained the powers and the one weaving an intricate web of deceit, not only in skin but in speech and entire demeanor as well.
Also, while characters are in our realm they are to look like us. They may retain their memories and slowly regain their magical powers, but they all stayed in human form. This could be part of our realm itself, part of the curse from Storybrooke, atau something different all together that we are not aware of yet.