As far as any risks of "false advertising" claims, I'd venture to guess there'd be none. So that'd not be an issue at all.

What would be an issue is the possiblity of alienating your own surfers and traffic by sending them off to a site they later feel ripped off by. It could cause them to distrust your outbound links and be less likely to join any of the sponsors you feature.

Further, some processors review the members' areas of the sites they process for, along with receive customer service emails from people who sign up for your site. And it's usually part of that processor's terms that a site doesn't mislead in their tour or promise what they don't deliver. So you could be sending traffic to a sponsor who is at risk of losing their processor.

Further still, if that sponsor is that bad you wouldn't be able to expect much in the way of rebilling/recurring revenue. Send traffic to a great sponsor and you could be earning a % off of lifelong members.

So, whereas the "false advertising" stuff wouldn't be an issue liability-wise or anything of that nature, it's not a very efficient use of traffic nonetheless.