It's best to consult the fine print of the program. Whether other people have gotten credit is irrelevant if the Terms & Conditions say it's not allowed. (It's like expecting a police officer not to give you a ticket just because other people are also speeding.)

According to the Hotels.com Rewards Terms & Conditions:
What is important here is that "you" is defined as the following:
Source: http://www.hotels.com/customer_care/...onditions.html

"You" means you...not your friends and family.