A method for operating a washing machine appliance may comprise a step of monitoring, with a sensor, a conductivity measurement of a tub of the washing machine appliance. The method may also include a step of receiving an input indicative of a selection of a self-clean cycle of the washing machine appliance. The method may further include a step of activating the self-clean cycle of the washing machine appliance. The method may also include a step of recording the conductivity measurement of the tub in response to the self-clean cycle being activated. The method may further include a step of comparing the recorded conductivity measurement to a first reference conductivity value. The method may also include a step of determining, based on the compared recorded conductivity measurement and the first reference conductivity value, the presence of a cleaning agent within the tub.