P- type transparent conducting oxide (TCO) thin films are the emerging new materials with a vast potential in transparent electronics. Many research groups are working on the preparation and characterization of these films but with a limited success. The Silver Indium oxide (AIO) and Copper Aluminum oxide (CAlO) belonging to the Delafossite crystal structure have shown p- type conductivity, however, the preparation conditions have a very narrow window for the growth parameters to realize p- type conduction. These materials being metal oxides, any small oxygen deficiency leads to metal rich films with sufficient free electrons. Thus, there exists a bipolar conduction in these p-type TCO films. The conventional Hall effect measurement with bipolar conduction (with comparable free carrier concentrations) and the electrons and holes having different mobilities leads to an incorrect sign of the Hall coefficient and erroneous estimation of the majority carrier concentration. In the present paper, Hall effect data from several groups (including the author's group) on several thin films (prepared with different growth conditions) of silver indium oxide (AIO) and copper aluminum oxide (CAlO) have been analyzed. The analyses clearly reveal that a lot of caution is to be exercised while measuring and interpreting the Hall effect data. The concept of Quantitative Mobility Spectrum Analysis (QMSA) for evaluating the mobility and carrier concentration in bipolar semiconductors is discussed in light of the TCO thin film samples. The contact potential difference (CPD) measurements by Kelvin probe technique to estimate the work function (and thus the Fermi level) in these p- type TCO thin films seems to be one of the potential techniques to estimate the p- type nature of conduction.