Thanissaro Bhikkhu wrote:
The teacher, meanwhile, must make sure not to regard the act of teaching as a repayment of a debt. After all, monks and nuns repay their debt to their lay donors by trying to rid their minds of greed, aversion, and delusion. They are in no way obligated to teach, which means that the act of teaching is a gift free and clear. In addition, the Buddha insisted that the Dhamma be taught without expectation of material reward. When he was once offered a “teacher's fee” for his teaching, he refused to accept it and told the donor to throw it away. He also established the precedent that when a monastic teaches the rewards of generosity, the teaching is given after a gift has been given, not before, so that the stain of hinting won't sully what's said.
All of these principles assume a high level of nobility and restraint on both sides of the equation, which is why people tried to find ways around them even while the Buddha was alive. The origin stories to the monastic discipline — the tales portraying the misbehavior that led the Buddha to formulate rules for the monks and nuns — often tell of monastics whose gift of Dhamma came with strings attached, and of lay people who gladly pulled those strings to get what they wanted out of the monastics: personal favors served with an ingratiating smile. The Buddha's steady persistence in formulating rules to cut these strings shows how determined he was that the principle of Dhamma as a genuinely free gift not be an idle ideal. He wanted it to influence the way people actually behaved.
He never gave an extended explanation of why the act of teaching should always be a gift, but he did state in general terms that when his code of conduct became corrupt over time, that would corrupt the Dhamma as well. And in the case of the etiquette of generosity, this principle has been borne out frequently throughout Buddhist history.
A primary example is recorded in the Apadanas, which scholars believe were added to the Canon after King Asoka's time. The Apadanas discuss the rewards of giving in a way that shows how eager the monks composing them were to receive lavish gifts. They promise that even a small gift will bear fruit as guaranteed arahantship many eons in the future, and that the path from now to then will always be filled with pleasure and prestige. Attainments of special distinction, though, require special donations. Some of these donations bear a symbolic resemblance to the desired distinction — a gift of lighted lamps, for instance, presages clairvoyance — but the preferred gift of distinction was a week's worth of lavish meals for an entire monastery, or at least for the monks who teach.
It's obvious that the monks who composed the Apadanas were giving free rein to their greed, and were eager to tell their listeners what their listeners wanted to hear. The fact that these texts were recorded for posterity shows that the listeners, in fact, were pleased. Thus the teachers and their students, acting in collusion, skewed the culture of dana in the direction of their defilements. In so doing they distorted the Dhamma as well. If gift-giving guarantees Awakening, it supplants the noble eightfold path with the one-fold path of the gift. If the road to Awakening is always prestigious and joyful, the concept of right effort disappears. Yet once these ideas were introduced into the Buddhist tradition, they gained the stamp of authority and have affected Buddhist practice ever since. Throughout Buddhist Asia, people tend to give gifts with an eye to their symbolic promise of future reward; and the list of gifts extolled in the Apadanas reads like a catalog of the gifts placed on altars throughout Buddhist Asia even today.
Which goes to show that once the culture of dana gets distorted, it can distort the practice of Dhamma as a whole for many centuries. So if we're serious about bringing the culture of dana to the West, we should be very careful to ensure that our efforts honor the principles that make dana a genuinely Buddhist practice. This means no longer using the tactics of modern fundraising to encourage generosity among retreatants or Buddhists in general. It also means rethinking the dana talk, for on many counts it fails the test. In pressuring retreatants to give to teachers, it doesn't lead to gladness before giving, and instead sounds like a plea for a tip at the end of a meal. The frequent efforts to pull on the retreatants' heartstrings as a path to their purse strings betray a lack of trust in their thoughtfulness and leave a bad taste. And the entire way dana is handled for teachers doesn't escape the fact that it's payment for services rendered. Whether teachers think about this consciously or not, it pressures them subtly to tell their listeners what they think their listeners want to hear. The Dhamma can't help but suffer as a result.http://www.accesstoinsight.org/lib/authors/thanissaro/nostringsattached.html