Disclosure of material connections.
When there exists a connection between the endorser and the seller of the advertised product that might materially affect the weight or credibility of the endorsement (i.e., the connection is not reasonably expected by the audience), such connection must be fully disclosed.
Example 7: A college student who has earned a reputation as a video game expert maintains a personal weblog or "blog" where he posts entries about his gaming experiences.....the manufacturer of a newly released video game system sends the student a free copy of the system and asks him to write about it on his blog......Accordingly, the blogger should clearly and conspicuously disclose that he received the gaming system free of charge.
I've never purposely concealed that fact that I had received a free kit for evaluation, but it may not have always been clear and conspicuous. Like you may have had to read the entire review to get to the conclusion where this tidbit was stored. Or, follow the post label to find the original post. Or whatever.