I find that if I know the author already and really like them but I see that it is a new book then I would always read the back cover. However, there are also cases where I never heard of the author before and would still be intrigued to red the back cover if the title and the image on the front of the book is appealing to me. I am more into mystery, horror or romantic books. I also like those that have pictures of people living in previous centuries.
If it is one of my favorite authors, I probably won’t even read the back cover and just go straight into it. Or it is one of my favorite genres and the back looks interesting enough, I’ll just go for it.
When I’m browsing for new books I tend to look at the spines along a shelf and if I find something that looks good I then read the back, if it then looks like it would be interesting (it doesn’t even have to be something that I would generally read, as long as it looks like a good read) i will then just delve in