"Soon comes the pale mare, and after her the others. Kraken and dark flame, lion and griffin, the sun’s son and the mummer’s dragon. Trust none of them. Remember the Undying. Beware the perfumed seneschal."
This prophecy seems useless to me even if it weren´t encrypted.
Don´t trust the Sun´s son? Don´t trust Quentyn Martell? Really?
This guy may not be pretty enough for her, but he seems completely sincere to me, and his father, whom he represents, is trustworthy too.
Don´t trust Tyrion?
Why? Tyrion shares her goals and is (for Westerosi standards) pretty trustworthy.
And beware that boat that sinks before it ever reaches your shore.
Should´t the prophecy warn her of Brown Ben´s treason, tell her whether Hisdar is trustworthy, who the Harpy is, and the identity of her poisoner?
Other parts may still prove to be useful, and I may have misread some, but so far this prophecy seems pretty lame and beside the point to me.