A Waterdhavian addresses everyone of known noble status as “lord” or “lady” (toddlers and young children usually as “young lord” or “young lady”). Brief bows are considered polite, but deep or florid ones are now often taken as mockery.
“Saer” (rather than “sir”), or “goodwoman” for a female, is used by those uncertain of a person’s status but not wanting to give offense. No offense will be taken (except when one Waterdhavian noble addresses another one as “saer”).
“Bladderblat” and “Glunder” are not real Waterdhavian noble surnames, but every city inhabitant or frequent visitor knows them. They are the two fictitious noble surnames most popular among Waterdhavian satirical broadsheet writers, minstrels, and tellers of rude street jokes. (“How did Lord Bladderblat decide if young Lady Glunder was a suitable match for his son? He tried her out himself, of course. Several times.”)
To address a Bladderblat as “young master” or “young mistress” is seen as a form of admonishment. (The word “miss” in the Realms means “fail to hit what you were aiming at”; it’s unknown as a form of address.)
Among adult Waterdhavian nobles (who, naturally, all know each other and see each other often at feasts, clubs, and revels), it’s an insult to address someone by the wrong title. Nobles refer to themselves as “we lords” or “we worthies,” and they speak of the ruling Hidden Lords and the Open Lord as “the Lords of the City.” Nobles usually refer to non-noble Waterdhavians as “citizens” when being polite, and “commoners” when being impolite.