If you wish to test products for companys, you should remember to write it on your blog.
On an “about” page, you should write that you will do tests, and you wont recommend produkts you dont like. Unless, you actually will, write anything a marketing company ask you to write. Not so reliable to your followers, so remember to keep the rigth to decide what you want to write.
You also need to write in your post, when you have a sponsores produkt that you are reviewing.
That makes it fair to your followers, they know why you have choosen to review that product.