There is a new scam method being used since January 2016. New users with fresh accounts and very little posts are showing up in the official MyBB community forums or contacting MyBB plugin authors directly.
They are looking for custom plugins and promise to pay money above average prices for the plugins. They do accept the usual process in this case: The plugin is developed and the plugin author does provide a testforum based on MyBB to test the plugins abilities by the customer. After that, the coder is being paid and the plugin is delivered.
The new scam method has been reported by two plugin authors already and looks like this: