When you play at lower levels then your opponents are doing everything at a lower level – including watching you. At higher levels of play then your opponents are watching you very closely. This is why it is easier to get away with playing so many tables at lower levels because your opponents are not scrutinizing your play as closely. Playing ABC on eight tables is easier to do and get away with than it is at say NL400. So your opponents are playing at a much lower level and so everything else impacts on that.
At higher levels then all of your opponents will be watching you very closely. Some will be using tracking software like PokerTracker while others will be watching you more closely. While tracking software watches your long-term game and highlights it far better than any human, it really takes a human player to spot short-term fluctuations in another player’s game. For example, if a playing is temporarily tilting then you need to know this immediately as the effect of that will be absorbed in large sample sizes.
Also, large sample sizes can be very misleading and even data can be very misleading in terms of how much short-term fluctuation there is. There are a very large number of short-term events that make up long-term results and this is something that needs to be done manually. You start to build an image when you sit down at a poker table simply by the way that you play your hands. Let us say that you have been raising pre-flop and betting and raising a lot recently. In this game then your image will depend on the level of players that you are going up against.
Unless you have been raising and re-raising like a maniac then lower level opponents will not notice a slight increase in your action from the norm. However, this will get spotted at higher levels and your opponents will adjust. Better players will adjust quickly and not let grass grow under their feet. So if you have say a loose-aggressive image and a certain player starts to play back at you then the table dynamic has changed. This is why playing so many tables at higher levels is very difficult because it is harder to spot the shift in table dynamic when you do this.
However, let us say that you have a hand like the 7-6s. You normally call a raise with this hand for two reasons. Obviously, you call because of your position and the fact that you feel that you can outplay your opponent. You also call the raise for both pot equity and fold equity. The pot equity comes from the pots that you can win with this holding and it also has big pot potential as it can make the nut straight. However, you can also bluff on a lot of boards as well and so you have good fold equity. But when you have been very aggressive then your fold equity decreases against stronger opponents.
They will not back down to your floating tactics or your flop raises on wet boards or other such plays. If you raise the flop on a board like 10c-9c-4d then they may just three bet you with A-J or even call your raise. When this starts to happen then you are either up against a very aggressive opponent that is looking to maximize fold equity or one that is reacting to your play. This is why you need to be very aware of your own image because your opponents will either contract or expand their ranges because of it at the higher levels of play.