Most marketers will request a review copy to fully understand what the product really is. This helps them to craft a good email swipe, which they will broadcast it to their leads.
For example, you wouldn't just write an article or an email swipe that goes: "Want to lose weight? Try the xxxxx program". That just stinks of spam and your conversion rate will be terrible.
A more effective way would be, "If you truly want to learn more about the secrets to losing weight effectively, just check out the xxxxx program by xxxxx. In this program she touches on the many factors that are indirectly causing you to keep that weight on. For instance, do you know the toxins in the air and environment around us can affect our metabolism? Yes! That's just one mindblowing fact that the program unveils. And in chapter x of the program, she unveils the surprising rules of weight loss. You MUST know these 3 weight loss rules if you want to lose weight effectively." etc etc
Now you may wonder, "Wait a minute, why can't they just get the email swipes or articles from the affiliate resources page then?" Well, it is overused. Let alone most newbie affiliates will just copy-and-paste those provided articles directly into their website - and we know Google doesn't like duplicate content. And even when a vendor provides a 'sample preview' or a small copy of the product, there's a chance every affiliate/marketer will be writing the same thing about the same provided content. And wouldn't it kill the conversion rate if a subscriber receives the same email swipe or happens to read the same article on multiple websites? That just kills credibility, and it makes the readers want to click "Back" or the "Unsubscribe" button too.
Screenshots and what not aren't really necessary. What matters is the delivery.
Now the question is whether is it worth asking vendors for a review copy. Unfortunately, most of the time, they wouldn't grant it to you unless you have large list of subscribers or a very good marketing strategy. If you're going to write review pages or by PPC advertising you can pretty much forget about it as they will just ignore you. Some vendors even set criterias like "Make 3-5 sales first and I will send you a review copy". And some will require several follow-ups - they want to know what's your strategy, and they will want to review it first.
You may wonder, "Why are these vendors being so difficult?" Well, you can't blame them as they fear it could be a fraud request (a customer pretending to get a free copy) or a fellow vendor is trying to grab a copy so they can plagiarize and make a duplicate product. Also, most vendors have the mentality to not entertain small-time affiliates... they only want to entertain platinum affiliates or superaffiliates, an affiliate with a large subscriber list, or fellow vendors to do cross-promotion.
Most of the time the only vendors that will grant a review copy easily to any affiliates are those small-time vendors with low gravity scores. They are desperately trying to get people to promote their product or to just appease new affiliates, so they will grant review copies freely. Regardless, I wouldn't advise it because these vendors will be messaging you incessantly asking you "how's the promotion going?".
You can always visit their landing page through your affiliate link, then try to close the browser so you will see their exit-splash page that gives some discount. Then buy from that discount while getting the affiliate sale. Use a fake email address though as you don't want your personal inbox to be spammed to death.
