Some sellers get away with selling poor quality products. The video link below shows how an insect killer actually has a loose electrical connection and works intermittently. This could have been easily checked by the seller before despatching to the customer.
Electric insect mosquito killer – costs Rs 699
Returns for replacement are expensive for the buyer and the some sellers return the same product with superficial repairs. With advances in technology, it is possible for certain sellers to intimidate buyers, so that they do not leave negative feedback or get negative feedback removed.