Used a lot by deposit scammers and con merchants like this lot.
The end-to-end encryption and other security makes it next to impossible to ID the scammers
If you find a girl who only offers WhatsApp as a comms route, or tries to switch conversations to WhatsApp, or requests a deposit via WhatsApp, then you are being scammed. Remember in most cases they can wipe any record of the conversation - removing any proof of it happening.
WhatsApp uses their regular mobile number, the same number as they would use for text and/or phone communication so I don't understand why anyone would be cautious of someone requesting WhatsApp usage
I find quite a few B2B massage girls convert quickly to WhatsApp so they can send photos that couldn't be put on Gumtree and I will continue allowing them to do that
I agree that anyone requesting a deposit should be avoided but don't agree that a conversion to WhatsApp in itself is a sign of being scammed.
The one App I never use because it is too anonymous is Kik