Let us not forget that Morraine referred to Blue Fairy as a ancient being who rules over the night….
I also read on another OUAT fansite that apparently A&E said in a podcast during or after S1 that Blue Fairy was good, not evil. Don’t know if its true just reporting. Regardless, I think shes evil as well.
I don’t think all the Sneak Fairy theories necessarily label her being evil. Just that she has a hidden agenda.