The Freys violated a sacred oath of the high houses of Westeros. Robb did as well with spurning the Frey girl.
I always wondered why Martin had Rob do this - besides later learning it was motive for TRW. At the time I read it, it seemed very Martin-like to demonstrate a young Stark repeating prior Starks' missteps. Here was where I really started to question the kidnapping story...and realized Jon was NOT a child of rape...then TKotLT iced that cake- to me, anyway.
I have a theory that Skagos's bad rep is only defensive propaganda. Kind of the opposite intent of "Greenland". Geographically, the majority of the main island's land mass lies South of the Wall, parallel to both Gifts, but well North of Winterfell - suggesting a cold but not full on brutal climate. It is an island, however, and ocean currents can have bizarre effects on climate...at least for parts of the land mass, if not all. I want to believe it will be Martin's Austrailia or at least Madagascar - wildlife and greenery different from anything found on Essos or Westeros, but with similar species as well.
I picture it more of a "winter wonderland" than a "club med" but I wouldn't be surprised to find it is a well-ordered society with laws and independent government, operating for generations outside the King's rule - Hence, distasteful enough to the free folk to prevent a mass immigration.
Hell, it could be where most of TCotF ended up, and are still there.
All that imagery I got from the unicorn dream. Haha.