Yet, in another place the Bhagavatam states that the same knowledge, if utilized in Krsna's service, is "factually hari-kirtana or glorification of the Lord":
"When advancement of knowledge is applied in the service of the Lord, the whole process becomes absolute. The Personality of Godhead and His transcendental name, fame, glory, etc., are all nondifferent from Him. Therefore, all the sages and devotees of the Lord have recommended that the subject matter of art, science, philosophy, physics, chemistry, psychology and all other branches of knowledge should be wholly and solely applied in the service of the Lord." --(SB 1.5.22p) Thus, with the proper consciousness we can utilize many things in Krsna's service that would have otherwise been considered to be material. These same things become spiritualized when in connection to Krsna's service.
In that spirit, I've come across a few other books and articles that I found helpful in my relationships and executing various household duties, such as effective communication with a child or spouse, and helps for getting motivated to do my tasks or for improving my service. In each case, I tried to follow the advice of Canakya Pandita who said:
"Even from poison extract nectar, wash and take back gold if it has fallen in filth."
It has not always been an easy task however; it requires a purified intelligence gained by hearing continuously for a long time from a bona fide spiritual master in order to discriminate properly. In the mean time, I learned the hard way how subtle maya can be and thus to steer clear of mostly philosophical speculations written by nondevotees, but now and then I did find favorable, practical advice that increased my understanding of or supported what Prabhupada taught regarding my various duties.
Also there must be a growing spiritual strength and vision not to use any knowledge gained to manipulate anyone nor to become puffed up in comparison to those who may in some way seem to be in ignorance. With knowledge comes responsibility to use it properly. Thus Krishna consciousness cultivation is the priority because it protects one from such offenses or from utilizing such knowledge for personal sense gratification, both gross and subtle.
Also there must be a growing spiritual strength and vision not to use any knowledge gained to manipulate anyone nor to become puffed up in comparison to those who may in some way seem to be in ignorance. With knowledge comes responsibility to use it properly. Thus Krishna consciousness cultivation is the priority because it protects one from such offenses or from utilizing such knowledge for personal sense gratification, both gross and subtle.
My conclusion, therefore, is that although the goal of a book- how to win the heart of one's husband, for example, as in the case of the marital advice that got trashed- is apparently materialistic and thus usually fit for the garbage dump, if I can read it with a heart towards Krishna and cultivating personal detachment and spiritual discernment; if my motive is to gain the Lord's pleasure by keeping the family intact and directed towards spiritual inquiry and His devotional service; and if the knowledge acquired is ultimately directed towards gaining the shelter of His lotus feet... It is a worthy read. And even if my motives are not pure at first, Krishna knows my heart and is all- powerful; anything done for or connected to Him will have a purifying effect and will eventually fix me on the right path.