Wow, that stinks. In my 12 years of traveling in India, I've never had this sort of thing happen, but that may be because I am a naturally suspicious person and tend to reflexively refuse anyone in an airport that comes up to me asking if I want a taxi. (The same goes for Moscow, Cairo, JFK, etc.) I always assume they are up to no good. Except when being picked up by uniformed hotel drivers, I never let go of my suitcase--there are always a million guys swarming around Indian airports offering to carry it for you--and I always just shake my head "no" when someone says "Taxi?"
Once at the Delhi train station, when I needed a taxi to the airport, I had some guy try to lead me all the way out of the station parking lot to a car parked on the street. About halfway through the walk, I just said no and turned around and walked back to the station (made possible by the fact that I was the one pulling the suitcase). He was yelling and trying to convince me to follow him, the cab was "right outside," but the whole thing just felt very sketchy. Maybe it would have been fine, maybe not, but I didn't feel like chancing it.
All I can suggest is to be more suspicious and keep your guard up. But I know from long experience that it can be tough to do this when you are tired and confused (as Indian traveling can make you).