While there are a number of outright deceitful things in FFX, such as the intimacy system and how Yojimbo works exactly, there's on thing that irritates me to no end:
Blitzball.
Perhaps not lying, but is definitely deceitful on the basis of it withholding VITAL information.
Some abilities have misleading descriptions. Anyone without a guide WILL NOT know what Volley shot does. It's one sentence long, and doesn't tell you anything useful.
Also, the subtleties of techcopying are never even hinted at. There's rules to it that are never elaborated on, but incredibly important.
Playing the game, you'll note that you can win abilities for your players. However, you'll also note that there are ALOT of abilities that your characters can have. So if you see an ability to be won, and don't know what it is, well you better have a guide, because the game isn't going to tell you if you don't already know. Is it an active ability? A passive ability? Is it any good? Enough to waste an hour playing through 2-3 matches to get? Who knows! You're on your own buddy!
In the very beginning, in your first match with the Luca Goers, this match is very hard not because the Luca Goers are very good. Nope, it's difficult because the game deliberately sabotages your chances at victory. First, while not a prerequisite, the mini-game to get the Jecht Shot is practically rigged against you from how it's sprung on you unexpectedly. Then when the game starts, you're NOT allowed to see your stats or arrange your team like you would in a normal non-story match. Then, in the second half at the 3rd minute, the game up and goes "Well, Tidus is too good of a Blitzball player, so we're taking him out and replacing him with Wakka, who is an inferior forward". You get no say in this, and changing characters is not possible in a normal game.
Certain characters are WAY WAY WAY better than others, but all stats travel along a linear, unchangeable line. So a minor character that is very sucky right now, could be a total team-destroyer 10 levels down the line. This is never told to you.
While the tutorial is nice, it never tells you about formations. As far as I know, there is no portion of the game the explains how formations work, nor does anything even hint that changing the formation might be useful. Personally, I never change from 'normal', because everything else causes the automated teammates to act retarded.