Fighting for big pots doesn't mean that you have to win at showdown. The biggest pots are usually ones that see a river card, so those players who have the courage to bluff in these pots will probably walk away (in some cases, at least) with good memories and with a significant amount of chips. But what if your opponent does it?
A bluff done incorrectly or at the wrong time is obvious, and you have an easy time in these cases - you just have to press the button labeled "call". You are in a tougher spot when your opponent is using bluffs correctly. That means not too often and not too rarely, and always in different situations with different sizes. I'll try and give you a few pointers to situations like these, with some examples.
Catching bluffs based on opponent's hand ranges
There are situations when you can find out almost exactly which hand your opponent might have. Of course you never know the actual hand, and you also don't guess randomly, but make your decision against your opponents' complete range of hands. Here's an example.
You are heads-up in a hand and you were lucky by hitting two pairs on the flop. You have J-T in your hand and the flop is Ts-Js-3d, but the situation isn't that easy because there is a spade draw on the flop. Your opponent checks and you bet in position. Your opponent calls. The turn is an offsuit 4. Your opponent checks again, and you continue betting. Your opponent makes the call again. The river in an offsuit 7 and your opponent opens with a huge bet, 3/4 size of the pot.
Based on previous information about the player you think that he will only bet this way with his straights, slow played sets and busted draws, and he would check with all other hands. That means your opponents' opening range is the following: all combinations with two spades, K-Q, Q-9, 9-8, J-J, T-T and 3-3. It's obvious that you beat the majority of this range, so that means you have to call in this spot.
Catching bluffs based on pot odds
As I already mentioned you'll see bigger bluffs on the river, so catching these has huge potential for a serious profit. Sometimes you make your decisions based on pot odds - let's take a look at an example for this. The pot was 12,000 before the river was dealt. You are heads-up and check with your border-line hand, before your opponent bets 4,000.
You saw earlier that this player is capable of mature bluffs when he has the opportunity. Because of this you feel that this could be a value bet but it could also be a bluff again. Unfortunately this time you can't conclude anything from the cards on the board. How do the pot odds help you in this case? You have to call 4,000 and you'll get back 20,000 if you win the pot, which means your pot odds are 20%. You only have to decide if your opponent would try bluffing less or more than 20% of the time in this given situation. If he would do it less often than 20%, you have to fold, but if you think that he would do this more often than 20%, then the call will be the correct decision based on maths.
As I said earlier, this opponent likes to bluff when he has the opportunity to, so due to the attractive pot odds you'll go with calling on this occasion.
Sometimes you'll find yourself in spots where it doesn't make too much sense to bet for value. These are mostly situations when there is a good chance that your opponent has a draw that has missed on the river. Also, it should be clear for your opponent that you have the better hand so he can't win at showdown. In these spots it makes sense to check the river and induce a bluff from your opponent.
A typical example where this skill is useful is when you have a strong starting hand – such as a big pair - which didn't improve. In this hand, you have pocket queens out of position. Your opponent calls your bets preflop, on the flop, and on the turn too. The board is 9c-8h-3c-2h-2d. If you think that your opponent called along with a draw, it's unnecessary to bet, because he'll just fold. It's much better to instead check-call, because this way your opponent might try to bluff.
Probably the most important rule to catch big bluffs is the following: never force it! Never try to catch a bluff at all costs, but if the right moment comes, don't be afraid to call even with weak cards.
Another golden rule is that you should never call down big river bets because you think that your opponent might bluff. Always try to find a reason for calling. Sometimes you can hit it without a reasonable explanation, but in the long term you won't be profitable in situations like this.