I'd add a third factor in. Cards, position, and (relative) chip stack. Those to me are the three weapons a player has. As a chip stack example, as long as your stack is enough to threaten serious damage to another player, it's a great weapon to use.
I look for situations where I have 2 of those in my favor. I will get this down to heads up. If I'm in good position, and I have say 40% of a guy's stack, an all-in forces him to work
ONLY with cards. If I win the hand, I have a bigger chip stack than him. (He has 100; I have 40. I go all in, there is 80 in the pot. I win, I have 80 while he is down to 60.) He can only win at that point by beating me on cards. He is more likely to fold with better cards because the risk of loss has a serious negative impact. If my chip stack is 30%, I can't make my chip stack work in my favor. He's more likely to call with the same hand. In that case, I'd want position and cards.
There are other factors as well. If he's gone into "fold his way into the money" mode, he's likely ONLY going to play with great cards once I put enough chips on the table.
Reiterating some points above:
- Trash is still trash.
- Good cards are still good cards.
- Position make a big difference.
But don't overlook chip stack. It's the third leg of the stool. Then as I mentioned, there are other factors that are more about playing either players or the situation. So there is a lot that goes into it. But the big 3 are cards, position, and chip stack.
It's stuff like this that makes poker fun.