That's one of those things I'd probably test before I assumed.
With Pinterest you see an image in the general feed, click on it, get taken to a "pin" page and have to click on it again to go to the website. Of course I'll only go through all that if I'm interested in the details of a product/topic.
What you're suggesting is to add another click to the process before I can really get to what I'm interested in. Perhaps if I'm going to buy a more expensive item I'll want to do research before a purchase. But, if it's a simple purchase all those clicks become tedious.
Plus, if you're using an affiliate link to a site like Amazon it could be more beneficial to play the click through/drop cookie #s game than to worry about optins, etc.