Here's the situation (purely theoretical, of course): You download a book from amazon because it sounds interesting, you start to read it, and you realize that there's no way you're going to be able to force yourself to plod through this thing. It's all tell, repetitive use of dialog tags, punctuation is wrong, paragraph breaks are in the wrong place, whatever else you want to imagine.

Do you:
1) Just move on
2) Give it a one-star and move on
3) Give it a one-star and try to come up with some platitudes or bare-bones statement that isn't too specific
4) Give it a one-star and try to write something that that will steer the writer to taking a course or something
5) Write a Jay-Sherman-esque flaying that will have the writer pull the book and never write again (note: I'm adding this one just for completeness. I don't think it's a serious alternative)

And for those who want to answer the bonus question: What do you think where there are a dozen or so 5-star reviews talking about how good the book is?