How do you know that your privacy and personal information are protected when you do all of these reviews? Certainly, you have to submit your name, address, and email address at minimum. Do you know what those companies do with this personal information? Do they sell it or share it with other entities? Many of the "free" offers that come up on the internet are only "free" when you submit your personal information.
You may get products in return for your reviews, but I believe there is likely a hidden cost that many people don't realize, and that cost could be the compromise of your personal information.
Even if you work with a company that promises not to share your information with any third parties, we constantly see government agencies, major corporations, and educational institutions being hacked all the time, so chances are, the more you put your personal information out there in a variety of different places, the more likely it is that some of it could end up in the wrong hands at some point in time.
There are criminal groups who spend every waking hour data mining, and others who are capable of incredibly sophisticated hacking. Identity theft is a very real risk whenever your personal information is compromised.
Personal information is the new currency in this digital age. You should assess the companies for which you'd like to submit reviews and learn about their privacy policies and how well they safeguard your information, and then decide if it is worth it to you to possibly risk your privacy in exchange for products.