The Big Boys' View
Among top-ranked players, doubling of slams doesn't meet with much approval (with the exception of the Lightner Double, to be discussed shortly). The reason is basically this: you stand to lose far more than you stand to gain. The presumption is that if top-level players have had all that time and space to explore, sure, they may be going down, but they're not likely to be down more than one. Which means the double adds 50 points against non-vul opps and 100 against vul. Whoop-de-doo!
Against that, if you give away some information on the distribution that allows declarer to make the contract, or if perchance you needle him into running to a makable 6 no contract, that's going to be one of the costliest doubles you'll ever make. I was the partner of one who embarked on such a double with a seemingly unassailable Q J 10 low in the spade suit initiated on his right in a 6 spade contract. Well, he was right about one thing: he certainly could have set 6 spades. But declarer ran to six no, at which my partner, nothing daunted, doubled again. And did declarer make it?
Well, he could have. When he led a singleton heart to the A K Q 10 x x in dummy and paused, I held my breath. But he couldn't bring himself to take the finesse and went down. Only some years later, looking at the hand, did I note that declarer had an iron-clad, risk-free major-suit squeeze against my partner. I don't recall whether we were vul not not, but either way the ratio of what we stood to gain vs. what to lose was pretty one-sided: If vul, we stood to gain 100 on the double vs. losing 1440, and if not vul, we stood to gain 50 points (!) vs. losing a thousand! 'Nuff said?
But sometimes if you can just get your partner to lead a certain suit, you may feel you're in a position to beat the contract, and of course, here you're not going for an extra 50 or 100 points (though you'll take them). A double in that case, necessarily by the partner of the opening leader, is called a Lightner Double, q.v. There isn't complete agreement about what the double means, but it's something close to calling for dummy's first bid suit, with some trimmings, discussed on that page, which also carries links to illustrations.
See The Lightner Double