Discrepancy in Caro's Pro Poker Tells?

[Key West]

I mean, I'm sure there are many, but this one is pretty blatant. In the "Bonus Tells" section of Tape 2, Caro says:

"...assuming that, unless you know differently of this particular player, that a soft check is really hoping that you don't bet. It means, 'I'm not going to declare war on you, please don't bet.' Soft check. On the other hand, and aggressive check: 'I check' is usually weak."

Now, wait just a confounded second here. If you're saying, "Please don't bet," you'd only say that because you have a weak hand. You want a bet behind you when you're strong so you can check-raise, right? So that means Caro is saying that a soft check means weak hand.

Then he says, "On the other hand" an aggressive check also means a weak hand? That seems like pretty useless information to me.

Am I misunderstanding something? Which is it? (I know it's never a sure thing, but given no other information, there has to be something you assume.)