Not to be sniffed at - phrase meaning and origin

One way of showing contempt for something is to raise your chin, avert or close your eyes, and sniff (once), supposedly practiced by snobs in ...  Browsephrasesbeginningwith: ABCDEFGHIJKLMNOPQRSTUVWXYZFull ListNottobesniffedatPostedbySmokeyStoveronMarch30,2007InReplyto:NottobesniffedatpostedbyLesleyonMarch30,2007:Wheredoesthephrase"nottobesniffedat"originateandwhatisit'smeaning?Onewayofshowingcontemptforsomethingistoraiseyourchin,avertorcloseyoureyes,andsniff(once),supposedlypracticedbysnobsinthepresenceofthelowerclasses."Nottobesniffedat"meansnottobescornedorunderappreciated.It'sratheranoldexpression,accordingtotheOxfordEnglishDictionary.s.v.sniff:"3.Toshoworexpresscontempt,disdain,disparagement,incredulity,orsimilarfeeling,bysniffing:a.Const.atapersonorthing.1729SWIFTGrandQuestionWks.1755IV.I.109Sothenyoulook'dscornful,andsniftatthedean.1837CARLYLEFr.Rev.I.VI.iv,CamilleDesmoulins,andothers,sniffingathimforit.1864{emem}Fredk.Gt.XVI.x.VI.262OurShopkeepersoftheRueSt.Honoréwouldsniffatsuchalodging.1888Times6July9/3Superiorpersons..willdoubtlesssniffattheexpressionofopinionuponthesetopicsbytheHouseofLords.b.Withoutconst.1837CARLYLEFr.Rev.I.VI.ii,DuskyD'Espréménildoesnothingbutsniffandejaculate.1871MRS.WHITNEYRealFolksxvii,Shedidnotsniff;shewasagreatdealtoomuchalady.1881BESANT&RICEChapl.FleetI.91Mrs.Gambittsniffeddisdainfully."SSx