Sorry for jumping in your discussion.
In my opinion, there are three reasons behind such ads:
Seller is desperately searching for a fool. Bethay bithae kisi tarah mera Chakka (sixer) lag jye
Ad is fake and the seller switches off his mobile right away. Given for fun sake only or to seek attention.
Ad placed with a very high demand just to get a reasonably good offer. Shall not sell but keep on telling other people that I have already received an offer of x amount for my car, but I shall not sell it below y amount. (And thereby having a fake sense of pride.)
Sorry if it sounded offensive to anyone.