Judging a book by its cover One of the main things I am using Stack Exchange for lately is finding math texts. As a community, I think we are generally very helpful at suggesting texts for all kinds of topics, but are we too helpful...?
What I mean is, for a given topic we have dozens of books to choose from. This isn't a bad thing; it means we have plenty of resources. But it can be a nightmare for a young undergraduate finding one that "clicks", especially when many different people are suggesting many different books to them! I've experienced this problem more than once before.
So my question is, do you have a nice, quick way of judging a text and seeing if it's for you?  Lately whenever I pick up a book I go straight to the contents and gloss through them. I'd be interested to hear other people's take on this though. 
 A: I am a serious lifelong book freak by anyone's standards. I will stick to math texts here. There are 4 things that generally dictate whether or not I will buy a book in no particular order. First is price, second is necessity, third is a serious concern for the potentiality that I could easily be sent to the hospital for being a hoarder (will I even read this book or will it just go on a shelf), and the last, very important one is whether or not I like the way it reads (do I understand/like it and wish to emulate the author's way of doing things).
If I absolutely have to have the book, I just bite the bullet. I just finished my MS, and needed a few specific articles by B. Van Der Pol for my thesis. I bit on $120 for a complete rare used set as I could not get them anywhere else for less. I only needed 6 papers, but the price was right, and I wanted to cite with authority. I am not currently in this "need" situation.
These days, I try to be selective mainly because of space and less so because of cost. I have no current necessity, so it is all about what I want to read. I like Springer pubs, I like Dover pubs, I like used books in general. 
The way that I decide to buy a book that costs a bit of money, is by finding some way to preview a bit of the book. I can usually find some of a book online, a part of a chapter will do. I do not have to immediately understand all of the book, but if I like the notation, and I am willing to emulate the author's style, I am partially sold. Dover pubs are an example of cheap books where I have had a hit/miss experience. Shilov's Linear Algebra: Bought it, sat on a shelf for a few years, and took me several other books and courses to where I can actually read the thing. It was not at my level at the time I bought it. It is officially redundant material in my library now, so I probably should not have bought it. Kleene's Mathematical Logic: Bought it, the notation is antiquated, but hey it's Stephen Cole Kleene! I took a gamble, and read half the book a year ago. I'll pick up interest again later, it is not trivial. I have many books on Non-Linear Dynamics. I chose them well (spent many hours making judgement calls), as it was my research. They are still worth the shelf space, and they all took serious hits to the spine by yours truly.
I generally have a mission in mind currently when I buy a book, and so I select one from a pile of collected possibilities. I read the table of contents, then I flip to any part of the book, and read for a while. (exploiting google books or whatever I can find in paper or electronically). They don't let you see the whole book in web previews, but I only need the table of contents and about 5 minutes of any part of the middle of the book to develop an impression. I then rate my choices, and cautiously buy a book.
I rarely recommend a book I have never read due to burning myself enough times on books that were above my level of understanding, or just painful to read due to antiquated (or unpopular) notation. Due to experience, it is fairly easy for me to find a book that works for me, but it takes time. I am cheap (frugal?), analytic, and cautious. Recommending a book for someone else is a bit more difficult. If the book fit's the bill and I know it is an armchair read, I will recommend it and ask them to tell me how it went. If I have not read it, and I have no idea how it reads, and it is a real math book, I will generally shut my mouth for fear of senselessly wasting someone else's money.
My solution to recommending books here, and I have recommended a few at least in comments, is to shut my pie hole unless I am absolutely sure I know what I am talking about. I know the book, I read the book, I am certain, or at least I would seriously like a copy of the book myself after applying my 5 minutes of purchasing research protocol. If the question is Non-Linear Dynamics, I have a few must have books to recommend. The rest is hit or miss, although any Springer Pub is a great book to me if you can get it cheap enough. Personal enthusiasm rules the day for me here.
For fun, I will conclude with an unsolicited book recommendation that has spent a very long cumulative time sitting on my shelf, but over the years has repeatedly been a godsend (and a really pleasant occasional pickup) even with the availability of free internet content over several years: The Princeton Companion To Mathematics - Timothy Gowers.     
