It's not that hard to make something true-but-misleading by way of implication. In response to whether he drank while underage, an American says "I drank when I was 18--it was legal in Lisbon."
By giving such a specific place, there's an obvious implication that it took place there, so he didn't break any law. Yet it's entirely possible he wasn't there, and is slyly banking on listeners just assuming the implication that he was.
If you catch him in the lie, the escape is easy: "I didn't lie. Both things I said were true." Indeed, he drank at 18, and drinking at 18 is legal in Lisbon--the fact he wasn't there is again left unstated. Now the trap is sprung: "If it seemed like I was lying, that's actually your fault for making an assumption."
In spite of catching him, you're now painted as the one who's screwed something up. This presence of this trap makes it dangerous to even call them out.
Watch as it comes naturally to this jew: "Indian immigrants do well [...so there's no danger in letting in another few million Mexican vagrants]."
He knows (and intentionally leaves out) that he's comparing the best of one group to the average of another. Anyone who doesn't notice he did that now buys the unstated implication that immigration is harmless, no matter who it is or what their skills are.
Such strategic omissions are only done to fool dunces into supporting their political causes (e.g. upping nonwhite immigration). If you call it out as a lie, you fall into a trap: they now get to say you're "misunderstanding" them, when you're actually one of only a small number who detected the real signal.
Smart people do not debate. That's not how the "war of ideas" is fought. The real battle is to present facts in a way which persuades dumber people to do their bidding.
