If you can handle the academ-ese, here's a journal dedicated to online advertising.
Fortunately, they have an RSS feed, which streams abstracts to your reader - and these may perhaps be a bit more readable than the full articles.
At the very least, sticking a few pages of this sort of thing in your consulting report will handily keep your customer from actually reading it, and help ensure that they take your word for whatever conclusions you've drawn:
Advertising value provides an overall representation of the worth of advertising to consumers (Ducoffe 1995). Existing literature suggests that consumers view advertising's ability to supply information as a primary reason for approving of it (Bauer and Greyser 1968). Research in online advertising also shows that advertising can offer value to Internet users in the form of more relevant information (Ducoffe 1996). When online community members possess a distinct group intention about the need for advertising, they should be able to internalize the notion that advertising benefits the community. As a result, these members should be more inclined to develop favorable evaluations of the advertising. We also hypothesize that they perceive a higher degree of value of advertising in the community:
H6: Group intentions to accept advertising in online social networking communities relates positively to perceived ad value in community sites.
Finally, cognitive studies of associative links suggest people tend to regard relevant information as more accessible in their attitude formation (Rodgers 2004). The more community members perceive advertising as relevant to the community themes, and thus more relevant to community members, the more likely they are to find such information useful, which should result in a higher level of perceived ad value. In turn,
H7: Perceived ad relevance relates positively to perceived ad value.
Come to think of it, slogging through this stuff is how I earn my rate.
Journal of Interactive Advertising