It seems like you could protect yourself from a Tazer by having a conductive metal in your clothing that would complete a circuit between the two prongs with lower resistance than your skin. Since people don't do this I guess it probably doesn't work. Can anyone explain why to someone without much electrical experience?
"Since people don't do this...", well, no one I know goes around wearing a ceramic-plates-enhanced bulletproof vest, but this doesn't mean it doesn't work. We need some hard evidence.
Of course you could turn the volume up to eleven and use a Faraday suit:
Depends on the type of the Taser. If it is a Taser gun, the projectiles would probably puncture the aluminium foil. You would have to wear something like a very thin but strong chainmail to be protected from that.
If it is a standard Taser, and the aggressor applies it to the aluminium foil, you would be protected as far as the aluminium is intact. Of course, it is very unlikely someone would prefer to tase your clothes over your exposed skin.
Overall, from the electrical point of view, you would be OK as far as the mechanical integrity of the armor is preserved.
Edit: an additional risk is that the metal may reach high temperatures due to the voltage present between the Taser's terminals and you may be burnt.