We heard this too, and were super cautious, but no one even tried to scam us. On the contrary, every taxi driver was wonderfully nice and friendly and made a point of asking us “Do you want me to just drive down the Strip? Do you want me to take X route?” I was very pleased.
It just depends on the situation. I’ve had cabbies who got lost and lowered the fare themselves. Others seemed to be deliberately racking up the meter, but I wouldn’t quibble over a few bucks. I’ve never had a gross overcharge, but I always tip, and if the fare seems high, the tip is going to seem low. It hasn’t been that much of a problem because when I take cabs it’s mostly been expensed. I would suggest not causing too much of a fuss unless there’s clear gouging. The local police won’t take kindly to the idea of someone refusing to pay the fare, which is what it may sound like even if you’re just disputing the amount.
New Jersey, with the exception of Newark Airport, is a negotiated fee and the driver has the right to refuse the trip. Most drivers I’ve had agree to double the meter plus return toll or a reasonable flat fee.
Newark Airport is the only flat fee in New Jersey in a medallion cab. Meter plus $15 surcharge and return toll.