  We reanalyze some of the critical transport experiments and provide a
coherent understanding of the current generation of topological insulators
(TIs). Currently TI transport studies abound with widely varying claims of the
surface and bulk states, often times contradicting each other, and a proper
understanding of TI transport properties is lacking. According to the simple
criteria given by Mott and Ioffe-Regel, even the best TIs are not true
insulators in the Mott sense, and at best, are weakly-insulating bad metals.
However, band-bending effects contribute significantly to the TI transport
properties including Shubnikov de-Haas oscillations, and we show that
utilization of this band-bending effect can lead to a Mott insulating bulk
state in the thin regime. In addition, by reconsidering previous results on the
weak anti-localization (WAL) effect with additional new data, we correct a
misunderstanding in the literature and generate a coherent picture of the WAL
effect in TIs.
