A while ago, I opened the DarkSega rip of ESB into AviDemux and started playing with the hue, saturation and color sliders, and I'm beginning to wonder if dialing down the yellow might provide more evidence for how blue Hoth originally looked.
The pre-GOUT transfers of ESB seemed to have a yellow push, I remember Hoth and Dagobah looking very neutral. (I vividly recall watching my old CBS/Fox tapes and wondering why Yoda didn't look green in Empire like he did in Jedi...)