Out of maybe 100 cab rides from Manhattan to Brooklyn, I have sensed reluctance maybe 5 or 10 times. Definitely get in the cab, close the door, and only then start talking destination.
Also, be aware that they have a counter-strategy if they don't want to take you. One time, my girlfriend and I got into the cab, told him where to go in Brooklyn, and within 60 seconds he had "car trouble". I was pretty sure sure he was bluffing and called him on it, and he said either (can't quite recall) he needed to go to a shop immediately, or he needed a tow. We sat in the cab for about 30 seconds, and then got out. He pulled away, almost certainly to find another fare.
Next time, I will get the details and file a complaint. If he really did have car trouble and a record of service, he should be able to have it dismissed.
Also, be aware that they have a counter-strategy if they don't want to take you. One time, my girlfriend and I got into the cab, told him where to go in Brooklyn, and within 60 seconds he had "car trouble". I was pretty sure sure he was bluffing and called him on it, and he said either (can't quite recall) he needed to go to a shop immediately, or he needed a tow. We sat in the cab for about 30 seconds, and then got out. He pulled away, almost certainly to find another fare.
Next time, I will get the details and file a complaint. If he really did have car trouble and a record of service, he should be able to have it dismissed.