've spent the last few months looking at marketing textbooks. I'm assuming that they are fairly representative of textbooks in general, and since this is a topic I'm interested in, it seemed like a good area to focus on.
As far as I can tell, assigning a textbook to your college class is academic malpractice.
They are expensive. $50 is the low end, $200 is more typical. A textbook author in Toronto made enough money from his calculus textbook to afford a $20 million house. This is absurd on its face. There's no serious insight or leap in pedagogy involved in writing a standard textbook. That's what makes it standard. It's hard, but it shouldn't make you a millionaire.
They don't make change. Textbooks have very little narrative. They don't take you from a place of ignorance to a place of insight. Instead, even the best marketing textbooks surround you with a fairly non-connected series of vocabulary words, oversimplified problems and random examples.
They're out of date and don't match the course. The 2009-2010 edition of the MKTG textbook, which is the hippest I could find, has no entries in the index for Google, Twitter, or even Permission Marketing.
They don't sell the topic. Textbooks today are a lot more colorful and breezy than they used to be, but they are far from engaging or inspirational. No one puts down a textbook and says, "yes, this is what I want to do!"