In order to avoid any scam, you need ask a few basic questions before making the payment to any vendors, such as:
1. Will I be getting generic emails or direct contact details of executives?
2. Same principle for the phone numbers
3. How frequent is the database updated?
4. What is the bounce rate?
5. What happens if you find an invalid contact, will they get replaced?
6. Apart from person name, emails and phone numbers, what other fields are available?
7. Can you export the entire database in XL or you are only allowed to send email campaigns? Actually, you need to pay attention here, because if you cannot download the list in XL, it does not make sense to go ahead with the purchase.
8. Always ask for a demo or sample. A live demo will be better, as you can see real time how the database looks like.