Since I wrote my post about how golf courses could use Groupon or similar companies' services, I have received many comments (pros and cons). Some were worried about the reputation and profitability of their golf course, others' concern was the bargain hunters. But I read about success stories as well where they were able to boost sales in low seasons and even retain some of these golf players.
Thanks to NGCOA Facebook page now I know that they have a guidelines in this topic. They recommend that "golf course should contract so that their posted rates and promotions are the best offer all the times, or the equivalent to the best available".
This tells me that the best you can do either run a promotion campaign without Groupon or only on Groupon. Without detailed explanation this does not make sense to me. Fortunately, the above quoted guideline is just a recommendation.