Hand reading is a critical element in becoming a big winning player at no-limit holdem. One of the most confusing things for a beginner is to recognize the possibility of your opponent making a backdoor flush. Commonly this happens on dry, rainbow boards where our attention is taken away from the possibility of the board running out flushing. One of the important things to watch is which cards on a rainbow board are not the flush suit.
Say we are playing in a $2-$5 game and we hold A ♥ A ♠ in the cutoff with effective stacks of $700. It gets folded to us and we raise to $20 on the button. The big blind calls. FLOP K ♦ 7 ♣ 2 ♥. BB checks, we bet $30 and he calls. TURN 5 ♣. BB checks, we bet $75 and he calls. River 3 ♣. BB checks, we bet $150 and he check raises all-in. It is extremely likely that our opponent holds K ♣ X ♣. It is very important to notice that the top pair on the flop was not a club. Let’s change the flop to K ♣ 7 ♦ 2 ♥. It is now unlikely that your opponent has made a flush unless he is making a light peel with 7 ♣ X ♣.
We can use the same logic when the board contains a straight draw or a front door flush draw. Let’s say we hold K ♣ K ♥ on a Q ♦ 2 ♣ 3 ♣ board. We bet and our opponent calls. Turn is an 8 ♦. We bet again and our opponent calls. River is a 7 ♦ and our opponent now makes a gross over bet all-in from in front. Chances are our opponent has a hand like A ♦ 5 ♦, A ♦ 4 ♦, 5 ♦ 6 ♦ or 4 ♦ 6 ♦ not a busted club draw. Again, it is really important to notice which cards do not contain the backdoor flush on the flop and how light our opponents will call us early on in the hand.
Some players will never peel with a 4 on a K ♦ 4 ♥ 2 ♠ board where others will call with any piece of the flop. Of the looser players they may very well make a backdoor flush with 2 ♦ X ♦ or a gutshot like 5 ♦ 6 ♦. I would not take this advice too far however, and start bluffing when backdoor draws appear. For the same reasons that we are good players and can recognize when we are beat most players at the lower levels are not as advanced and will not fold big hands to our bluffs.