Bluffing is a familiar strategy in poker. Sure you've polished your game and practiced you poker face, but have you considered that it may not always work every time? If you haven't, well here's a wake-up call for you. There are circumstances when it wouldn't work even if you've got the art form down.
One sensible circumstance when not to bluff is when you're playing with beginners. This group of players wouldn't even know that you're bluffing them. While this is the intention of the bluff, the point is, they wouldn't be scared off so easily. When they get weak hands, the innocent aggression of their play works to their favor. They wouldn't really go on considering odds and probabilities. Rather, they are more engrossed with making their own hand and thinking that luck's on their side all the time.
Another situation is when you're faced with players who can sniff you out like a bear out for food. Now, we don't want to exploit the social order in poker however, we're not going to deny that it exists. At the end of the day, there are players out there who are better than you. When you do bluff repeatedly, you'll be out of the game so quick because they will backfire. While this really wouldn't call for abandoning the strategy, the point is that it should be done occasionally.
Also, shun a bluff when you feel like putting an obnoxious player straight. Emotions have little room in poker especially when high stakes are involved. While you want to prove your bluffing prowess to someone who made a bad comment at a previous hand, you'll lose focus on your own game. If you want to prove them wrong, do so with consistency and not with reckless arrogance.
A bluff only works in opportune circumstances with the right group of opponents. You'll be wasting your skills if you carry them out with a group of beginners, so that's a definite situation when not to bluff. On the other hand, if you're playing against more shrewd opponents, do it from time to time and know when to catch them off guard. Lastly, don't bluff without focus. There will be times when irksome players will say something that undermines your skills. So shun a bluff when you only want to demonstrate a point because it leads to carelessness and the last thing you want to do is to prove them right.