When you enroll yourself in an affiliate and are willing to make money by referring your blog's visitors to a particular site through the affiliate link that you have posted in your post, it is better to hide that link with another link. It's just because when a potential customer hover's over the link, he can see that there is often a word in the link like "ref=2378283" or "Ref Id 2903ws9" etc. It gives a clear indication that the link is going to give you a monetary benefit. Even though the offer you posted was genuine, still the visitors may feel that this is a trick to earn money and it's a waste of time to them. So it is better if you hide the link behind the words you have written to be clicked in order to go to that particular website.

How Can You Do It?

Use a good site for link conversion. For example Tinyurl.com or Bit.ly (Which Twitter Uses). It gives you a unique small link in place of your original link and it is FREE.

Try it and avoid making a bad impression.