Mentioned above is the 20 reservation rule. That was issued in early 2008. At the time there were serious rental problems in that professional renters had control of large numbers of points and were making large numbers of reservations at 11 months out for highly desirable rooms at highly desirable times (such as Christmas) and then renting those reservations via advertisements online. They could make large numbers of reservations via a combination of owning points, having points transferred to them (there was no limit to number of transfers the professional renters could take into their accounts at the time), and they could be added to any number of member's accounts as associate members and make reservations.
DVC took three steps to limit the power of professional renters. It limited transfer to one per use year, limited to four the number of accounts on which anyone could be an associate member, and adopted the 20 reservation rule as Disney's interpretation of the rule in the POS's that says you cannot engage in in renting for "commercial purposes." That 20 reservation rule issued at the time, which you cannot find on the DVC site anymore, reads as follows:
"Commercial Use Policy. The Disney Vacation Club (DVC) Public Offering Statement makes it clear that DVC memberships are intended for personal vacation use. The Declaration of Condominium and the Membership Agreement for the Resort expressly limits the use of Ownership Interests to personal use and prohibits use for "commercial purposes," - a pattern of rental activity or other occupancy by an Owner that the Board of the Association, in its reasonable discretion, could conclude constitutes a commercial enterprise or activity.
"DVC Members may make as many reservations as they desire. However, if, in any 12-month period, a DVC Member desires to make more than 20 reservations, the DVC Member shall be required to establish, to the satisfaction of the Board, that all of the reservations made by the DVC Member in such 12-month period are for the use of accommodations by the DVC Member, the DVC Members family and/or the DVC Members friends (collectively, Personal Use), and not for commercial purposes. If, in any 12-month period in which a DVC Member attempts to make more than 20 reservations but is unable to establish, to the satisfaction of the Board, that all such reservations are for Personal Use and not for commercial purposes, all reservations in excess of the first 20 reservations shall be presumed to be the use of Vacation Accommodations for commercial purposes in violation of the Declaration and the Membership Agreement (the Multiple Reservation Rule).
"Enforcement of this policy will be the responsibility of DVC Member Services as follows. For each reservation made by a DVC Member, Member Services shall determine, before confirming the reservation, the number of reservations made by such DVC Member which are occurring or have occurred in any rolling twelve-month period in which the reservation then being made will occur. If, as a result of Member Services review of the DVC Members reservation history, the reservation the DVC Member is then attempting to make violates the Multiple Reservation Rule and the DVC Member has not established, or cannot then establish that all of the DVC Members reservations, including the reservation then being made by the DVC Member, are for Personal Use, DVC Member Services will not honor or confirm the reservation and the DVC Member shall be advised that the reservation violates the Multiple Reservation Rule and the prohibition on use of Vacation Homes for commercial purposes. For reservations canceled for violating this policy, the cancellation shall be deemed to be a cancellation by the DVC Member and the provisions of the Home Resort Rules and Regulations relating to cancellations (including, without limitation, Sections 5(d), 13 and 14) shall apply."
Though the combination of new rues did not entirely eliminate professional renters; it greatly reduced the problems that existed.