See also
Despite all these “representing more strength than you actually have” tactics, sometimes your flop or turn bets will get called, and you reach the river with a hand that is not as strong as you had portrayed it to be. Many weak players would bet big in this spot with their bad hands or missed draws to represent a monster, and to make the opponent lay down the better hand. With their mediocre made hands like two pair, they would tend to check to induce a bluff bet from an opponent who might have a busted draw.
With a busted draw or weak hand
Assuming I have been lead-betting all the way, and the possible draws don’t seem to have gotten there, I am not that fond of the “betting big” option that many players will use. “Why is that?” you may ask. Well, it’s because in this situation, these same players will often bet much less or try to sell their hand if they really have a big hand, while betting big if they are bluffing. For that reason, I like to turn this pattern around, especially against players who expect you to bluff big if you miss yet milk a little if you really have a hand. To them, a small, even-sized bet of about one-quarter or one-third of the pot will often look like a milking bet: many good players would fold their one-pair and even two-pair holdings in that spot, not wanting to reward your obvious value bet. So, against players like this, a relatively small bet may get almost as many folds as a big bet would - with this difference, that you now lose a lot less money if your bluff attempt fails. However, you don’t want to bet too small, as your opponent may be induced to start bluff-raising you, or just get curious to see what you have now that calling is so cheap.