A siaolang thrives on negative energy. 
Negative energy is the burning coal of a siaolang. 
A siaolang does not want to believe that other people believe her. 
A siaolang creates conflict in order to generate negative energy from others.
If you believe what a siaolang says about herself, there is no conflict, and there is no burning coal for her to feed on.
I say, believe her !  If everybody believes a siaolang, to the siaolang it's like lighting a fire in water.