Harrington´s Law

[jacknine]

(first post on here)
Hi,
Those of you who read Harrington on Hold ´em vol. 1 are probably familiar with what Dan calls "Harrington´s Law": there´s always at least a 10% chance your opponent is bluffing.
Personally, playing low limit NL games online, I find this very true. However, when reading through people´s posts with hand equities, nobody ever seems to take this into consideration. Why is that?

J9.