I don't understand how you can decide whether to 'accept a product at all' rather than leave a negative review. How can you know what it's like before you've seen or tried it? And then as discussed above, you won't give a negative review as that leads to you getting less stuff/money. Sorry I cannot get my head around this. You and others like you are doing consumers no favours at all. It's hard to find actual real unpaid-for reviews for many things now, and that is wrong. Yes, the companies will pay you, and you take their money, but still it's deceptive on the part of all concerned.
What I mean is, if a company only wants a positive review (which isn't always the case - you often get sent things for an honest review - they don't have any expectations but they are usually pretty confident in their product) then I wouldn't accept it. You can't agree to write a positive review before you've even seen the product!
I won't accept something for the sake of it, so I research before I accept any product from any company, and if I feel that the other reviews aren't great or the product isn't something I'd need/use I wouldn't accept it. I have a small house and it would end up full to the brim of clutter if I accepted everything lol.
It's just another form of advertising - it's no different to a TV ad when you've got some clear skinned model saying how this spot treatment is amazing, even though she probably never had spot to begin with. As long as it is clearly disclosed as an ad that's what it is. It's not a new thing.