I've participated in charging debates a lot.
I learned the best thing to do is to apply common sense. The DM eventually allows a charge or not.
As much as I love to charge as a PC, as DM I would never allow a charge around a corner, or zig zagging.
Charging means, with a howl, you increase speed, and with full might crush into the enemy.
According to the rules, you can charge around corners, zig-zag, whatever, so long as you move two squares and end in a square adjacent to the target that was the closest adjacent square from where you started teh charge.
Common sense need not apply. I had a VERY hard time understanding the rule at first because it DOESN'T follow common sense/physics. See again this handy guide:
1. Calculate the square you are starting the charge from.
2. Calculate the closest square(s) adjacent to the target from that square.
3. Is/are it/they unoccupied?
4. Can you legally move to that/one of those square/squares?
If yes to three and four, you can charge. It really is that simple. 1. Calculate the square you are starting the charge from.
(Caveat: so long as you have moved two squares.)
You can even back up squares, move laterally, whatever and THEN start your charge from that square as a Charge is a Standard Action.
Of course a DM can adjudicate to disallow it any time he/she wants.