Strategy guides - What's your take?

Most major game releases today are accompanied with an official strategy guide. Whether they are actually necessary for each and every game is definitely debatable. Game guides have been around for quite some time, and they've evolved a whole lot in terms of presentation and production. Hell, there's even limited/collectors editions of guides these days. There's no doubt that there's a market for game guides, even though similar information can often be found online with a simple search.

So my question to you is: What's your take on strategy guides?

Do you find that they spoil the game entirely, and that it's poor sportsmanship to make use of one?
Do you feel that it contributes to the experience as a whole?
Is it a waste of cash when you can find guides of similar content on sites like Gamefaqs?
Have you purchased a guide before? If so, which, and were you satisfied with it/them?