tho they tend to be washed out, Super Pastels have noticeable outlines. i think the remaining coloring is more of an influence from the Fire (headstamp). Edit: i also think the washed out is an indication of it being a Super, a Pastel would be blushed.
hold them back and breed them out is the only way for sure. if Pastel's and Pastel combo's are in every egg, it's a Super. (but real experts may still weigh in)