I have to say, your example seems pretty poor. Let’s assume both you and your opponent are strong, thinking players, and actually look at the action:
–Preflop–
Player limps, you check. Since you have 9-2 off suit this is understandable.
–Flop–
A(h) 5(s) J(s). Note that at this point the pot is 2 big blinds and 1 small blind, so there are 250 chips in there. You decide to bet 325 chips, this means you are making a bet that is bigger than full pot. Whether or not the total number of chips is very large, this is a big bet relative to the pot size. For your opponent to call your opponent has to have some pretty good equity. So, what are you hoping to get called by? Here are some options:
Pairs:
An A will certainly call you. a J also might, depending on the player (and on your own table rep). a 5 will probably fold. The reason a 5 is likely to fold is obvious if you consider what your own bet represents: I think you are representing one of 3 hands. A pair, a straight draw, or a flush draw. If you have a pair, then a bare 5 is probably losing, and if you have a draw then the 5 is doing a little better, but cannot expect to keep calling when you continue. If I was holding a 5 and you bet into me I would probably fold. If I did not fold, I would instead opt to raise instead of calling. If I raise then at least I might charge the draws. Of course if you get raised then you have to fold because your hand is garbage.
Pocket pairs can usually be treated the same as a bare pair I think. Any pocket pair lower than a J is probably going to fold, and QQ and KK are only barely stronger than a jack is (they are also really unlikely. Remember your opponent limped preflop).
Two pairs and trips: These are certainly never folding. There is a chance that they will raise you to kick out the draws, but they also might call hoping to get more value if you are bluffing or if you have a pair yourself.
Draws: Flush draws and straight draws might call, or also might raise. Raising with a draw gives you a good chance to just win the pot on the spot, and if not then your draw will either strike it big if you hit, or be in a good position to continue bluffing on later streets. It is also possible that a draw will call, especially considering your bet is so big, but this is not certain.
Air: Air will not call. If you had bet smaller you might get called by a float, but since your bet is bigger than the pot then it does not make sense to call with air.
So your opponent calls.
—TURN—
Now a 10c hits and you decide to bluff for 575 chips. Note that the pot is now 1000 chips. This means that although your bet has more chips in it, it is actually smaller than your bet on the flop. This bet is just over half pot, while your flop bet was bigger than the whole pot.
So, what are you representing? If you had trips or two pair, you would either bet bigger, or check. The reason you will not bet half pot is because 10c just came in. This completes a straight draw. If you bet half pot and get raised, you will have to fold your two pair or trips. That sucks! This is actually a very good incentive for your opponent to bluff-raise you here.
If you had one pair, this line makes sense. It is not so painful to fold a one pair hand vs. a raise because your hand does not have that much value. On the other hand, it is very unlikely that you would make this bet with a jack, because your hand just isn’t that strong.
If you hit your straight draw, this line makes sense also. The smaller bet induces your opponent to call or raise you, which is exactly what you want.
If you still have a flush draw, then this line is a smi-bluff and also makes sense.
Hence, if your opponent sees you bet, he will put you on the following range:
a)Aces, b)a straight that just hit with the 10, c)a flush draw, d)air. Option d does not make too much sense, but you are playing this so it must be in your range, and if your opponent has been watching you carefully he should know this. Option b) is also a little bit unusual because it means you checked KQ preflop. Most of your range is really just a pair of aces or a draw.
So, lets remember what your opponent’s range is:
If he had trips or a two pair then he only loses to a straight. You have not made it very expensive, so he will call.
If he had an A he only loses to a straight as well, unless you also have an A and he is outkicked. It is, however, very unlikely that you have an A with a strong kicker because you checked preflop: If you had an A and a good kicker then you would probably have raised.
If he has a J he only beats the bluffs and semi-bluffs. Depending on how often he thinks you make that kind of play, he will either call or fold.
If he had a straight draw, then he either just made a pair of tens or he hit his straight. If he hit the pair of tens he is in the same spot as if he had a J (but also still has a straight draw to go with it, so the likelyhood of calling is a little bit higher). If he made a straight then he has you beat, so he will not fold (he might raise).
If he was on a flush draw, he could do almost anything. Calling, raising and folding are all plausible depending on his style. Calling is based on the plan to bet the river almost no matter what card comes. Raising as a semi-bluff is another interesting plan, the idea being that you either hit the straight or you didn’t. If you do not have the straight you will probably have to fold, and if you do then there is still a chance he will hit the flush on the river and since your hand is so strong you will probably call again, giving him a gigantic pot. Folding also makes sense of course, especially if he thinks you like to call river bets.
So what hands are you going to get to fold? It looks like you will fold out the jacks some of the time, flush draws some of the time, straight draws with tens in them (unlikely, but possible!) and nothing else.
So I would say this is an example of a bad time to bluff, and a bad sizing to do it with. You are only targetting a very small portion of your opponent’s range, and your own value range is pretty thin.
On the other hand, this would actually be a pretty decent example of a good time for your opponent to raise as a bluff. If he makes a big raise here, pretty much the only hand you can call with is a straight. If you call and a spade comes on the river he can even bluff again, especially if he has the ace of spades himself.
Also of note, you said you bet the flop for information, but then you didn’t use the information that you gained when deciding what to do on the turn.
Anyway, your opponent folded and you won the pot. This probably means your opponent had a pair of jacks.
EDIT: Per Sassy_Sarah’s suggestion, I have changed the capitalization of a couple sentences to make it clearer. Also I added a couple sentences about pocket pairs on the flop.