They are scammers. They called on a Saturday morning and left a 5 minute long voice mail that was nothing but mechanical noise. I blocked my number and returned the call to get a message saying that the survey I was called for has ended. I've gotten no less than 50 of the same type of call from different numbers - pretending to be a survey to get around calling numbers on the DNC list.
That in itself is an indication that they're disreputable. Other sites indicate they're offering vacation packages.