Originally Posted by Justin749
When you see a table where everyone is calling and very loose, you might wanna step away.
Failure to understand the concept of equity (http://www.cardschat.com/preflop-concepts.php):
Equity can be explained as your share of the pot. Every hand you are dealt has a certain chance to win before all the cards are out; even if someone has pocket aces on the same deal, your 72o still has a small chance to be the winner. This percentage is called your equity - the amount of the pot that you in some mathematical sense "own." This equity will change as cards are being dealt, of course - if you have 72o vs. AA preflop, but you flop two pair, your equity has shot through the roof - you may now suddenly be a favorite to win, whereas before the flop, you were a big dog! With a large equity, you figure to win more than your share of the money that's bet, so raising is a good idea.
Let's look at those pocket aces a little more closely. Every starting hands chart recommends you to raise with them, so let's examine why: If you have pocket aces and you're up against 9 other players (whose hands you have no information on yet, let's say that you're UTG), your average equity will be 33%. This is how well aces fair against 9 other hands that call all the way to the river; ~30% of the times, the aces win. A bit of a bummer, perhaps, that your aces won't even win a majority of the time, but at least you have a better chance of winning than anyone else at the table. But also keep in mind that it's highly unlikely that everyone else will call all the way to the river, so perhaps your winning chances are a bit better than 30%.
But what if everyone calls anyway? Then you're surely in trouble - 7 times out of 10, you won't win the hand.
Look here: 3 times out of 10, you will win 20 bets (the big blind + your raise), and 7 times out of 10, you will lose 2 bets (your raise). A win of 60 bets, and a loss of 14. That's a net win of 46 bets! That's HUGE! It's true that you won't win more than half the time, but that's okay because you're paying considerably less than half of the money going into the pot. This is why we raise with AA: It has a huge equity preflop, and anyone who calls you is paying you more than they're winning. AA is so likely to win the pot in the end, that you can safely raise now and expect to show a profit in the long run. The same, of course, holds true with KK and QQ.
But what about AK? This so called "drawing hand." It's true that it's considerably weaker than AA, but it's far from helpless. And even against a large field of opponents, AK will still win more than its fair share of the pots. You flop a pair on average once every three times with AK, but for the same reason that AA is okay even if it only wins 30% of the pots, AK is okay even if it only gets help once every three times. It will simply win more than its share of pots, even against many opponents. Especially when suited.
The lesson here is that with hands that have strong equity, you should raise preflop. How strong a hand's equity is depends on what it's up against, of course, and you can never be quite certain of that. In one specific case it doesn't matter: If you have AA, you can always raise safely. KK, on the other hand, is in big trouble if it finds itself up against pocket aces, but the risk of that happening is so small that as a general rule of thumb, you should always raise with KK preflop, as well. However, with hands such as 55, do they really have a big equity vs. 4 other opponents preflop? Hardly. In fact, they are probably pretty far behind. But they can still be played profitably, and for the same reason that suited connectors can.