That's a valid point. Women who have read about the pickup artist techniques report that the techniques still work on them even when they're aware the person is using them. On the other hand, SWIM says that being aware of various techniques has helped him guard against HR methods on the basis of "Oh, now he's moving into stage x, next he's going to...". SWIM would say that it depends to what degree you're predisposed against the person using them.

Be aware that some techinques are more obvious than others. Some are really obvious when you know they exist, but also really obscure, so you won't know they're being used unless you've read about it before.