If I am taking an official city SPQR taxi from a stand, or find one to flag down, is it legal to negotiate a flat rate from point-to-point before getting in, and agree to keep the meter off?
For example, an offer of 12 euro from Pyramide metro area to Spagna metro (just as an example).
If this isn't something that isn't commonly done, and I do decide to just let the meter run, other than making sure I'm in a licensed taxi, what can I do to protect myself from overcharging? If I have a GPS phone - I can make sure they take a direct route. Is there anything else I should watch out for? I know the starting rate for night taxis is approx. 6 euros, correct?
If I feel I am being scammed, for example, the driver demands extra money on top of what the meter says when we get to our destination, what should I do? Will they get violent if I refuse to pay the extra?
Also, are taxis so bad there that I need to be concerned some cabs with SPQR on them are actually FAKES that take people to dark streets where they are mugged by a gang? (Yes... this is serious question!)