Tidus says he remembered Jecht singing the hymn of the fayth... But this is impossible, because Jecht never went back to Zanarkand after going to Spira (not in human form anyway)... So umm, what?
The Al Bhed know the Hymn of the Fayth, too. Does that make things impossibly difficult? Maxx Power is wise and intelligent, but does that make him a bad Red Mage Pirate? Levian sucks, but does that make him suck?