One-Page Registration Sites
A site that asks for nothing more than an e-mail address, first and last name cannot possibly be a Market Research Company. You should see a red flag coming up. A legitimate Market Research Company, on the contrary, usually asks for detailed information so they can better target panellists for available surveys.
No Company Information
Questionable survey sites do not provide any information regarding their business. On the other hand, legitimate Market Research Companies willingly disclose details like their company headquarters, history, reward system, contact and support information, FAQs, etc. Typically, this can be found on the 'About Us' page.
Market Research Companies usually pay you USD2-UDS45 for a survey. A survey that promises you a payment of anything more than this sounds too good to be true and is most likely a fraud. You should trust your gut feelings on this.