Origin and exact meaning of "taken to the cleaners"

I know the meaning of this phrase by context, but the German analogs are no literal translations of this phrase and very dissimilar metaphors, meaning roughly:

being tricked into something being pretty unprofitable for you (deal, duty or else)

A short Google search didn't show in-depth explanations. What is "cleaners" referring to here? Is this American or British English and in which branch arose this phrase?

Cleaners refers to a professional dry cleaning business. See this from The Phrase Finder:

TAKEN TO THE CLEANERS -- "Relived of one's money or aspirations, perhaps by flimflam; easily bested. The advent of professional dry cleaners not so many decades ago brought about this modernization of the earlier phrase 'cleaned out.' James H. Vaux, in his 'New and Comprehensive Vocabulary of the Flash (slang) Language' defined the older phrase as follows: 'Said of a gambler who has lost his stake at play; also of a flat (dupe) who has been stript of all his money.'" From "The Dictionary of Cliches" by James Rogers (Ballantine Books, New York, 1985).

Etymonline has the "fleecing" sense from 1932, but I've turned up the broader sense used in print as early as 1929 from American mystery writer Dashiell Hammett's Red Harvest:

Frequency in print has increased fairly steadily since then.

Edit, 1/17/12

Etymonline has updated its entry on cleaner based on some antedatings found by @Hugo. It now lists "fleecing" sense from 1921.

This explanation looks pretty convincing to me...

Take to the cleaners is a more recent term for the 19th century term 'cleaned out' - being stripped clean of everything of value.

It may have helped the expression gain/retain currency that it's also suggestive of not having/leaving money in the pockets of clothes that you take to the cleaners, and that if you did leave any by accident, the cleaner would probably just keep it and say nothing to you.

To take (someone) to the cleaners has three meanings. The Concise New Partridge Dictionary of Slang and Unconventional English defines them:

cleaners noun: take someone to the cleaners, 1 to thrash someone, UK 1976. 2 to thoroughly swindle or rob someone, US 1907. 3 to forcibly strip someone, UK 1997

The American Heritage Dictionary of Idioms defines the first two meanings as slang; early 1900s and you can find German equivalents here. There's another variation, put the cleaners through (someone).

Here's some earlier antedatings to Callithumpian's 1929, all three published in the USA.

A letter from W. H. Emrick printed in the April 1914 Electrical Worker (Vol. XIII, No. 12, page 182, pdf):

At present we are not in a position to say what the outcome will be but have high hopes of taking the Employers' Association to the cleaners.

The 1921 Lady Luck by Hugh Wiley (Project Gutenberg: plain text):

Starting in the sunshine of Lady Luck's smile, the Wildcat cleared the hurdles of financial ruin and rambled into the stretch soggy with a cloudburst of hard luck. He staked his last pair of ten dollar bills on a throw whose momentum carried him to the cleaners.

The 1922 Riders Up! by Gerald Beaumont (archive.org: read online, or plain text), page 175:

"Oh, Susanna !" he cried. "I got you!" I win the pup with the screw tail! Twenty minutes for a new book, gents; and — believe me or no — Susanna and I are going to take you all to the cleaners!"

This book is about horse racing and gambling (a lot of gambling) and contains many similar references to cleaning for taking money. Cleaned up:

"The old firm's grown a bit, Billy. I had contracts for ten bottoms at sixty-eight dollars a ton when the war broke out. Cleaned up a million and a half on each contract almost overnight. Sold five ships and put seven and a half millions into the South American end of the business. Caught the market right on sugar — another five millions. Now we've got three millions in Liberties, ten ships worth one hundred and eighty dollars a ton, a warehouse valued at two million, and we're cutting into the British trade from one end of the south coast to the other. Billy, my boy, you've been through hell, now I want you to have your share of fun. Forty millions in assets, and I rolled it up all for you. Help yourself, boy — hit 'em hard and high, the old man loves you!"

Clean sweep:

He was rather hopeful of a clean sweep in the gaited saddle class, but the moment the spot-light disclosed the final challenger, Van Buren drew a quick breath and acknowledged himself beaten.

Clean-up:

Between them, they made pretty much of a clean-up in the National Coursing Stakes and the North American Field Trials.

And finally, this is a nice one:

The truth was that there were many visitors in Dominion Springs who were exactly in the Kid's predicament, for the town boasted seventeen bathing-places, one hundred and fifty games of chance, and a race track. For its size it was undoubtedly the greatest cleaning establishment on the continent.