I am afraid I will be the dissenting voice here.
Poker is about finding an edge and exploiting it. Gathering intelligence on your opponents is simply part of the game. I'd argue that it is one of the purposes of sites like CC. Why else are we expected to post so much content? It explains questions that explicitly ask what you would do in situation X.
Now, I cannot afford to pay full whack for a popular HUD like HM3 or PokerTracker (pro editions). But even using a free version is incredibly useful intel. There is a huge difference between HiJack 3 or 4 betting with a VPIP of 15% vs HJ doing the same with a VPIP of >50%.
Keeping notes on players is also important. You should understand what they are capable of. Straightforward? Tight and Aggressive? Loose and passive? (My favourite opponent!). You want to be able to play against some of these folks.
Remember, it is not all about the cards. It is about the players and the mistakes they make which you will need to capitalise on. You may choose to enter pots with absolutely nothing if you can catch a player with a known defect/leak. You may see overbets following such players in an effort to isolate them (ie forcing others to fold) and exploit the weakness.
At the end of the day, it is these players which fund the game. It is your job to find them and set up a direct debit into your stack. There are simply too many players out there to NOT do this. If you don't have a database of intel growing on a daily basis, once again, you are drifting backwards while the others continue to surge forward.