There's no way for you to track another company's sales to see if they're accurately counting them.
You either trust them, or you don't.
As for the celeb thing, what difference does it make to you what they have in the members area? They don't offer a partnership program, its strictly a per signup and they absorb refunds and chargebacks.
The only thing you should be concerned with is whether or not the tours convert. (And the celeb sites are their best converting last time I checked
)