These days most chess publishers provide pdf samples :)
http://www.everymanchess.com/extract/Caro-Kann%20MBM%20extracts.pdf
Also, Amazon has the 'LOOK INSIDE!' feature and in this case it shows more content than the publisher's sample. For example, it includes the index of variations.
Yeah, that doesn't tell you WHICH line. It's a useless blurb. You order this book online and you have no idea what you are getting.
I disagree. If I see that it's a repertoire book for Black, I can assume that it is only going to focus on one way to play for Black and cover various White variations, as opposed to the other way around. If you have already decided you are partial to one branch of the Caro Kann going in, I don't think it's unreasonable to expect you to do a little more research. Another way to do this is, if you're buying through Amazon, to read the reviews. Usually people will spoil which lines the author recommends.