certainly in my book "punters" is not derogatory.
I think the use of "punters" by the media and now by people referring to their clients is one of the most appalling terms I have ever heard.
The word punter may refer to:
Australian colloquial term for festival patron
A speculator in the stock market
A gambler, particularly an amateur betting on horse racing or a player in the game of Baccarat
A beginner skier or snowboarder, especially one with particularly bad style
Someone who uses a punt (boat)
Punter (football), a position in American or Canadian football
The Punters, a Newfoundland traditional music group
Punter (protocol), a file-transfer protocol
Ricky Ponting, nicknamed Punter, a former Australian cricketer
A British, Australian and Hiberno (Irish) English colloquial term for a paying guest or customer, especially
a patron of a public house
a patron of a brothel
a customer of a prostitute
more recently, a paying atendee of a festival or other event
Punter (ship), a Dutch flatbottom ship type
Australian colloquial term for voting citizens
Punternet an escort rating service
But I am getting off topic.