Are there specific ponies that react badly to sun fading ?

[Sukey]

I'm considering sun fading  Streaky and maybe Quackers. Do they do ok? Are there ones that shouldn't be sun faded?

[prancingstag]

I'm not sure if there's a comprehensive list, but I think you have to be careful with a lot of the whites and pinks - they can be prone to going brown or burnt. And I think purples don't always react very well... Sometimes head/body mismatch there can't be fixed or can even be made worse by sun? I think MB Thundercloud is known for having unfixable mismatch.

[slyons]

You want to check this thread out, great info!!!
I unfortunately tried to sun fade Cherry Treats before reading up on it 

http://mlparena.com/index.php/topic,325963.0.html

[mlp4me]

I'd keep Quackers out. Especially if she has brown spots... Not a lot of white ponies aside from the Rice Krispies baby fade well. Any pony can burn. You have to watch them closely and rotate.

[hathorcat]

Any pony that is prone to age marks can cause you an issue unfortunately. However in general whites/light blues/light purples tend to be the biggest sufferers. From the 2 you mention, I would be super careful with Quackers; you could have no problem at all but I have seen a lot of concerns with her discolouring in the past. Just keep an extra special careful eye on her and be aware that you may make her worse unfortunately. Its a bit of a judgement call.

[Sukey]

So when you say they might burn- does that mean the spots can become darker or the pony gets discolored? If it becomes discolored does it yellow or turn different color?

[Deep Purple Crystal]

I'd say most lightly coloured ponies, although I think the light blue type reacts the worst to sun fading really.

[hathorcat]

So when you say they might burn- does that mean the spots can become darker or the pony gets discolored? If it becomes discolored does it yellow or turn different color?

Usually what it means is that the body discolours or goes brown in colour (sometimes a creamy brown sometimes an outright brown). However if there are age marks it can mean larger brown areas may appear around smaller age spots.