The Oracle's prophecies are fairly straightforward. They don't really use weasel words. The only one you could argue is the posthumously one, but Durkon is still dead and his body is returning to Dwaven lands. That it's walking there by virtue of an evil spell instead of being carried in a coffin is beside the point. Durkon is returning after his death. For all we know, he may never be raised.

Haley solved her affliction by not questioning an unexpected event.

Vaarsuvius said the four right words to the right person at the right time for the wrong reasons.

Belkar asked if he would kill any of the following (not all of them), and he did, by killing the Oracle.

Roy's prophecy was screwed up by Roy, not the Oracle. The Oracle even tried to get him to fix his wording so it wouldn't send them in the wrong direction.

So we've had no indication that the Oracle lies or intentionally misleads people with his prophecies.