Like many people my worst airport experience (in fact worst travel experience) can be summarised in three letters: BOM

I have travelled to my fair share of "non-Western" airports and never had a problem but Mumbai is the deepest pit of travel hell on the planet. Everything is nasty - immigration (2 hours*), baggage wait (1 hours), wait for transit bus (1 hour), ripped off by everyone from porters to bogus "airline reps", kidnapped by a taxi driver and driven into the Mumbai back streets and held hostage in a hotel room. And that was on one trip.

You couldn't pay me to transit through BOM again.

* that's before you find you can use the 5 minute "fast track" VIP line for $10.