IRIN, the UN's humanitarian news service, puts together a "factbox" on Palestinian "refugees."
It has the usual distortions that we are all used to (like saying that UN Resolution 194 gives Palestinian Arabs the right to return, without mentioning the important caveat there and all the other sections of that document that were vehemently rejected by the Arabs and accepted by Israel.) It also uncritically accepts the definition of "refugee" that is unique to Palestinian Arabs alone and no one else, that guarantees that the "refugee" population will grow in perpetuity.
One small part of the article shows how a lie can take hold. It says that "Estimates vary greatly on the annual rate of new displacements, but Palestinian sources cite up to 20,000 newly displaced persons per year. Reasons for new displacement include Israel’s construction of a separation barrier in the West Bank and Jerusalem, the construction of illegal Jewish settlements in the occupied West Bank, the revocation of residency rights and house demolitions. "
20,000 people losing their homes every year? When a dozen people who built an illegal structure are forced to move out it generates international headlines for months. The idea that there are 20,000 cases like that every year is an insane fiction.
Yet the UN has no problem citing it as an authoritative statistic, without mentioning any other source that might put the number at closer to, say, 200.