Deleting a post does not make it become "faded".
Deleting a post hides the post from all users with <10K reputation (except for the question owner himself and moderators). Those who are able to see the deleted posts (owner, moderators, and 10K + users) will see the deleted post appear with a pink background, as opposed to the usual white background, indicating that the post is deleted.
Faded posts are those post with low scores. See this discussion on Meta.SO.