From SPG Terms and Conditions (emphasis added):
An "Eligible Rate" is the rate an SPG Member pays for a stay in a guest room at an SPG Participating Hotel unless:
A. the guest room was booked through a tour operator, online travel channel or other third party channel including, without limitation, expedia.com, hotwire.com, priceline.com, orbitz.com, booking.com, travelocity.com, ctrip.com, and elong.com.
B. the guest room was booked at a group rate as part of an event, meeting conference or organized tour, and the SPG Member does not directly pay the SPG Participating Hotel for such room;
C. the guest room was booked at a tour operator, wholesaler, or crew room rate including, without limitation, STARNet and STARPRO;
D. the guest room was booked at a business, employee or friends and family rate;
E. the guest room was provided complimentary; or
F. a voucher or third party award (e.g., Aeroplan room award, Air Miles room award) was redeemed for the guest room.