The emote is a simple
Any of the perfumes sold by Lovely Merchants will qualify; none of the colognes will.
You must have drunk enough alcohol to have received the statement saying you are "totally smashed". (Note that alcohol is not sold in Undercity. Vinemaster Suntouched in Silvermoon City is nearby via the Orb of Translocation.)
All of these have to be active when kissing: the "totally smashed", the rose petal effect, the perfume buff. You may have to drink more than the minimum alcohol to ensure you don't sober up too much before getting your kiss in.
Sraaz is a gnome located around the Great Forge, in Ironforge; he is walking around the outer rim of the forge selling pies. Jeremiah Payson is a Forsaken located under the bank in Undercity selling Cockroaches.