Exit Polls can be just as inaccurate as regular polls

[mr_lebowski]

3. Depends on how one defines 'being wrong' ...

The inaccuracy you refer to is accounted for by confidence intervals. The statistics essentially say "I'm 95% confident that the true (i.e. total population) value is X".

And if you CORRECTLY sampled completely randomly ... and applied the correct formula (z-score vs. t-score, etc) ... that 95% confidence interval will basically always be correct ... because you're only saying you're 95% sure

Of course your sample size can't be too tiny. But beyond a certain threshold (which is actually pretty low if the population has a normal distribution of values), having more samples just (generally) decreases the width of your confidence interval