No second and third party links

I am annoyed to these people keep on coming to my blog and disguisedly commenting good points to my sponsored posts but purposely just comment to links their own product's website. It is unfair to the advertisers who paid me. This is my reason why comments are keep for approval first before i published them because i won't allow strange links get in. I should have also protect those advertisers who trusted my blog as good marketplace. And i must be sure that paid post i made for them is exclusively for them only and there is no second or third party links. For so many blogs in the blogosphere accepting paid post but many blogs denied . Luckily my blogs are chosen and i am so thankful about it. I am just only sad that one of my blog is blocked by google but still hoping that will restore as soon as possible.