Internet marketers live on the World Wide Web, hiding in a dark niche, waiting to fall into the trap of innocent users who are victims of their talents. They offer guarantees that they know you're too lazy, promises that even legitimate agencies can't make, and a price that always seems to be on the edge of what any sane person would pay.
It is very easy to lose a lot of money for these people and it is often difficult to get them back even after going through the "guarantee" process. So how do you know if the product you're looking for is good?
The only real answer is word of mouth. Before you buy, do some research on the product and see what other people have to say. Reviews, comments, opinions, complaints ... you have to see them all. It may be annoying, but it's worth it.
Using dangerous shortcuts - too many "review" sites are trading partners, hoping to convince you to buy from their website and hoping to immediately benefit from your good user experience. You can tell these people that they have almost nothing wrong with their product - and only rate one product (or closely related product group) at a time.
It's best to find a website that ranks a broad product group, isn't afraid to tell you the good from the bad, and deviates from flashy graphics, bold headlines, and other sales signs.
There are a few tricks you can use to keep working if you can't find an honest review website. If you're considering buying a digital product and want to know if it's good or not, here's a "Do and Don't" list:
DO: Google for the product name in quotes and the following: "inurl: forum". This will take you to a forum (message board) where you can (usually) get honest feedback about the product you choose.
DO: Google for the product name in plus quotes: "+ waste". Of all the words people often use to describe a bad deal, "waste" is a word traders rarely use. Criticism is another good thing.
YES: See money-back guarantees for most of these products. The default is 60 days - but that's not the important part. The important part is: will the product have a noticeable effect within those 60 days? If you are not guaranteed to work within 2 months, this guarantee does not apply.
NO: Google for the product name, together with any of the following: cheat, suck, work, work, review, opinion, comment, or the plural or gerund of those words. These are all words of marketers deliberately basing their headlines to tempt you.
NO: Buy * anything * that has more than two similar "reviews" on the first two pages of Google. These are products that are sold through marketing rather than true efficiency.