Even the lowliest servant views with disdain a vendor's marketing pitch. The same servant wonders why his employer does not respond to his entreaty for more paying work.
I have joined, belonged, participated in, etc. many marketing groups, tip groups and networking groups the purpose of which is to drive business to each of the members of the group. After more than 15 years of participation in such groups, I have come to realize that the best business comes and goes to those who believe they are there to give referrals, not so much as to receive them.
The hackneyed term for this phenomenon is "giver's gain," but I think its bigger and broader than that. It has to do with being viewed with sincerity, and this sincerity is what naturally attracts people to you. If there is a perception that your participation is phony, only a few people in the group will not notice, because your subconscious will off-gas deceit, while your mouth attempts in vain to correct the odor.
So my pithy thought for the day is that the next time you are at a conference or a seminar, and you meet people whom you perceive to be obnoxious salesmen peddling their business cards about like an underemployed lapdancer in Las Vegas, consider the possibility that you might need a dance. Because it is sometimes that sincere open-mindedness you exude that will bring the next customer to your booth.