Bet-folding, raise-folding

I thought about writing an article about the idea behind bet/folding (and raise/folding) in limit hold 'em. I figured I'd start off a discussion about it first, to get an idea of what I need to explain about it.

So, the concept of bet/folding: A good example of when you would want to do this is when you have a decent (but not monster) hand, you're heads-up on the river, the board is scary and you're in first position. Let's say that you have

A♥K♥

and the board is

K♠Q♣5♠6♠2♠

Your opponent is loose, but passive. What's your play here? (The symbols don't show very well, but the board has four spades, so if your opponent has any spade at all, he beats you.)

Here is where you may consider to bet/fold. Your opponent may call with a pair (e.g. a king or a queen) but would not bet these hands if you checked. Furthermore, if he has the ace of spades (and less often, the J of spades) he will raise, and you can safely fold. This way, you get maximum value when you're ahead, which - most of the time - you will be.

Raise/folding employs the same principle, but now your opponent bet first. The board doesn't have to be quite as scary for this to work. Let's say that you have K-K on the button, and the board is T-8-5-T. You raised first in and the big blind called. On the flop, you got checkraised, and decided to slowplay and raise him on the turn.

Now, on this turn, you can raise/fold against non-tricky opponents. When you raise this turn, he will almost certainly only come back at you with trips or better, so if you get re-raised you could - in theory - easily fold. This requires a "not tricky and not tilting" read that you trust a lot, though.

These were the best examples I could think up right now, but perhaps they're enough to explain the basic idea I'm after.

Anyone have any trouble with the concept? I struggled with it a bit in the beginning, because it seemed silly to me to risk a bet on the river with a decent hand and fold if I was raised, instead of just check/calling and getting to showdown for the same price.

Doesn't the first example depend somewhat on how the betting has gone previously? I assume you bet pre and post flop and on the turn, but if he raised back, especially on the flop, would you be out of the hand assuming that that meant he had a set? I'm assuming at some point there would have been an indication if he had a set or 2 spade cards, so that to get to this point, you think it likely that he doesn't have these hands.