Monger in the normal definition is simply a dealer. Somebody who trades goods. A common use of the word monger can be found in connection with war. A warmonger is a person who somehow deals with war.
However, this is not the route we are interested in. In Pattaya as well as everywhere else in South East Asia when you hear the term monger you are talking about a sex monger. Those are people who trade with sex. In my opinion a much better type of trade than war, even society is often seeing it otherwise. But this should not be our topic now. A sex monger is somebody who deals with sex and this could be all kinds of people, women, and men, old and young.
In Pattaya sex mongering is very normal. Thousands of women sell happily sex to men. For women it is an easy way of income and for men it is simply fun. The women come from all over Thailand and the men from all over the world. That’s why Pattaya has the nickname to be Disneyland for adults.