I got into an Apache cab by chance at Sky Harbor and they drove me to the Westin Kierland Resort. My driver (Alex, Russian guy) was very friendly, though he bemoaned the plight of the cab driver a lot of the time. I liked him and wanted to feel bad for him - which resulted in my paying him in cash instead of credit card and giving him a nice (not overly nice) tip, as well as calling him back to arrange my return to the airport.
After he beat the same horse all the way back to the airport, though, I started to wonder if he just grouses about how terrible business is and how crummy the rates are vs. expenses just to get bigger tips. Maybe, maybe not. I still paid in cash and tipped appropriately the second time, since I'll never see the guy again. But it made me a tiny bit uncomfortable.
The thing that saved it was that he offered, and made good on, a 20% discount for repeat business. I'd like to have faith in humanity and like the guy, so I've given 4 stars. He drove safely and attentively and was personable and super on-time. Pretty much all you can ask for.