It depends upon the campaign requirement. Some gambling campaigns require their participants to gamble as a part of their rule.
I promoted many services in my signature space and many of which were gambling websites. None of them had such requirement. And if it has I would never join it in first place.
Generally, you should know about what you promote at least to be able to answer anyone who asks you about that service.
Actually the one I am wearing now is my first gambling-related one. So I would not know if there was any such requirement,,, but it does seem odd.
Personally, I have joined only a few campaigns in my lifetime on this forum,,, 2 I will not speak off because they never even paid up (and I actually liked the product so it was doubly sad) but I always will only promote something I like and I use. I think it should be a requirement to understand the service you use, or why promote it at all?