Whispering "sweet nothings"

Where does the term sweet nothings come from? What is an example of a "sweet nothing"? Does the term connote sincerity or has it been hijacked to represent deceit and seduction? After all, the devil does whisper sweet nothings into my ear all the time.

Edit: Wiktionary carries a rather extreme definition of the expression:

(idiomatic) Insubstantial or romantic words that are only meant to flatter, woo, or seduce.

Examples of usage:

• 1904, George Gissing, Veranilda, ch. 28:
  Hearing such words as these, in the sweetest, tenderest voice that ever caressed a lover's senses, Basil knew not how to word all that was in his heart. . . . Side by side, forgetful of all but their recovered peace, they talked sweet nothings.
• 1922, James Joyce, Ulysses, Episode 16:
  [T]he facts, to make matters worse, were made public with the usual affectionate letters that passed between them, full of sweet nothings.
• 2004, Joe Klein, "Does Bush Really Get Us?," Time, 25 April:
  It is difficult to know how accurate this portrait is, and how much of it consists of sweet nothings whispered into the author's ear by loyal retainers.

I found this reference where the the question was asked and one user answered:

"The earliest example of "whisper some sweet nothing" I can find is from a poem in a London magazine called Belgravia by Mary Elizabeth Braddon 1876."

Quote:

As low he bends o'er her he loves so dear,

To whisper some sweet nothing in her ear.

Also from Volume 98 of Belgravia, January to April 1899, the same author, Mary Elizabeth Braddon, had a short story that included a reference to "sweet nothings":

"...The lips that had declaimed words of passionate entreaty, threats of bitter revenge, now lovingly whispered sweet nothings into the ears of that wee frail being, lying 'twixt life and death in her own home."

As far as whether the "sweet nothing" is sincere or meant to coax, mislead or cajole the recipient into some (presumably romantic) situation, I'm not sure there is a hard and fast "rule" on that. The intention and response are purely in the hearts of the whisperer and whisperee. ;-)

OED has very little about it, except for a surprisingly late earliest citation. I had imagined that the term would have come from Shakespeare.

sweet nothings n. colloq. sentimental trivia, endearments.

1900 Fazl-i-Husain Diary 20 May in A. Husain Fazl-i-Husain (1946) ii. 35 The sweet nothings so often talked of in the romantic descriptions.
1934 C. Lambert Music Ho! iii. 212 The blues have a certain austerity that places them far above the sweet nothings of George Gershwin.
1973 M. Amis Rachel Papers 119 Half the guests, including DeForest (after a minute of sweet-nuthins with Rachel), had wisely got the hell out as soon as dinner was over.

I don't think it has been "hijacked" at all. Endearments can be sincere or deceptive; there is no judgement in the term itself.